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Radiological response and inflammation scores predict tumour recurrence in patients treated with transarterial chemoembolization before liver transplantation 被引量:5
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作者 Daniele Nicolini Andrea Agostini +7 位作者 Roberto Montalti Federico Mocchegiani Cinzia Mincarelli Alessandra Mandolesi Nicola L Robertson Roberto Candelari Andrea Giovagnoni Marco Vivarelli 《World Journal of Gastroenterology》 SCIE CAS 2017年第20期3690-3701,共12页
To investigate the prognostic value of the radiological response after transarterial chemoembolization (TACE) and inflammatory markers in patients affected by hepatocellular carcinoma (HCC) awaiting liver transplantat... To investigate the prognostic value of the radiological response after transarterial chemoembolization (TACE) and inflammatory markers in patients affected by hepatocellular carcinoma (HCC) awaiting liver transplantation (LT).METHODSWe retrospectively evaluated the preoperative predictors of HCC recurrence in 70 patients treated with conventional (n = 16) or doxorubicin-eluting bead TACE (n = 54) before LT. The patient and tumour characteristics, including the static and dynamic alpha-fetoprotein, neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio (PLR) measurements, were recorded. Treatment response was classified according to the modified Response Evaluation Criteria in Solid Tumours (mRECIST) and the European Association for the Study of the Liver (EASL) criteria as complete response (CR), partial response (PR), stable disease or progressive disease. After examination of the explanted livers, histological necrosis was classified as complete (100% of the cumulative tumour area), partial (50%-99%) or minimal (< 50%) and was correlated with the preoperative radiological findings.RESULTSAccording to the pre-TACE radiological evaluation, 22/70 (31.4%) and 12/70 (17.1%) patients were beyond Milan and University of San Francisco (UCSF) criteria, respectively. After TACE procedures, the objective response (CR + PR) rates were 71.4% and 70.0% according to mRECIST and EASL criteria, respectively. The agreement between the two guidelines in defining the radiological response was rated as very good both for the overall and target lesion response (weighted k-value: 0.98 and 0.93, respectively). Complete and partial histological necrosis were achieved in 14/70 (20.0%) and 28/70 (40.0%) patients, respectively. Using histopathology as the reference standard, mRECIST criteria correctly classified necrosis in 72.9% (51/70) of patients and EASL criteria in 68.6% (48/70) of cases. The mRECIST non-response to TACE [Exp(b) = 9.2, p = 0.012], exceeding UCSF criteria before TACE [Exp(b) = 4.7, p = 0.033] and a preoperative PLR > 150 [Exp(b) = 5.9, p = 0.046] were independent predictors of tumour recurrence.CONCLUSIONThe radiological response and inflammatory markers are predictive of tumour recurrence and allow the proper selection of TACE-treated candidates for LT. 展开更多
关键词 Liver transplantation Recurrence-free survival Hepatocellular carcinoma Radiological response Locoregional therapies Inflammatory markers Selection criteria
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Role of glioma stem cells in promoting tumor chemo- and radioresistance: A systematic review of potential targeted treatments 被引量:1
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作者 Edoardo Agosti Marco Zeppieri +4 位作者 Mattia Ghidoni Tamara Ius Alessandro Tel Marco Maria Fontanella Pier Paolo Panciani 《World Journal of Stem Cells》 SCIE 2024年第5期604-614,共11页
BACKGROUND Gliomas pose a significant challenge to effective treatment despite advancements in chemotherapy and radiotherapy.Glioma stem cells(GSCs),a subset within tumors,contribute to resistance,tumor heterogeneity,... BACKGROUND Gliomas pose a significant challenge to effective treatment despite advancements in chemotherapy and radiotherapy.Glioma stem cells(GSCs),a subset within tumors,contribute to resistance,tumor heterogeneity,and plasticity.Recent studies reveal GSCs’role in therapeutic resistance,driven by DNA repair mechanisms and dynamic transitions between cellular states.Resistance mechanisms can involve different cellular pathways,most of which have been recently reported in the literature.Despite progress,targeted therapeutic approaches lack consensus due to GSCs’high plasticity.AIM To analyze targeted therapies against GSC-mediated resistance to radio-and chemotherapy in gliomas,focusing on underlying mechanisms.METHODS A systematic search was conducted across major medical databases(PubMed,Embase,and Cochrane Library)up to September 30,2023.The search strategy utilized relevant Medical Subject Heading terms and keywords related to including“glioma stem cells”,“radiotherapy”,“chemotherapy”,“resistance”,and“targeted therapies”.Studies included in this review were publications focusing on targeted therapies against the molecular mechanism of GSC-mediated re-sistance to radiotherapy resistance(RTR).RESULTS In a comprehensive review of 66 studies on stem cell therapies for SCI,452 papers were initially identified,with 203 chosen for full-text analysis.Among them,201 were deemed eligible after excluding 168 for various reasons.The temporal breakdown of studies illustrates this trend:2005-2010(33.3%),2011-2015(36.4%),and 2016-2022(30.3%).Key GSC models,particularly U87(33.3%),U251(15.2%),and T98G(15.2%),emerge as significant in research,reflecting their representativeness of glioma characteristics.Pathway analysis indicates a focus on phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin(mTOR)(27.3%)and Notch(12.1%)pathways,suggesting their crucial roles in resistance development.Targeted molecules with mTOR(18.2%),CHK1/2(15.2%),and ATP binding cassette G2(12.1%)as frequent targets underscore their importance in overcoming GSC-mediated resistance.Various therapeutic agents,notably RNA inhibitor/short hairpin RNA(27.3%),inhibitors(e.g.,LY294002,NVP-BEZ235)(24.2%),and monoclonal antibodies(e.g.,cetuximab)(9.1%),demonstrate versatility in targeted therapies.among 20 studies(60.6%),the most common effect on the chemotherapy resistance response is a reduction in temozolomide resistance(51.5%),followed by reductions in carmustine resistance(9.1%)and doxorubicin resistance(3.0%),while resistance to RTR is reduced in 42.4%of studies.CONCLUSION GSCs play a complex role in mediating radioresistance and chemoresistance,emphasizing the necessity for precision therapies that consider the heterogeneity within the GSC population and the dynamic tumor microenvironment to enhance outcomes for glioblastoma patients. 展开更多
关键词 Glioma stem cells CHEMORESISTANCE RADIORESISTANCE Molecular pathways Targeted therapies Systematic review
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Extravasated contrast volumetric assessment on computed tomography angiography in gastrointestinal bleeding:A useful predictor of positive angiographic findings
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作者 Laura Maria Cacioppa Chiara Floridi +11 位作者 Alessandra Bruno NicolòRossini Tommaso Valeri Alessandra Borgheresi Riccardo Inchingolo Francesco Cortese Giacomo Novelli Alessandro Felicioli Mario Torresi Pietro Boscarato Letizia Ottaviani Andrea Giovagnoni 《World Journal of Radiology》 2024年第5期115-127,共13页
BACKGROUND Gastrointestinal bleeding(GIB)is a severe and potentially life-threatening condition,especially in cases of delayed treatment.Computed tomography angiography(CTA)plays a pivotal role in the early identifica... BACKGROUND Gastrointestinal bleeding(GIB)is a severe and potentially life-threatening condition,especially in cases of delayed treatment.Computed tomography angiography(CTA)plays a pivotal role in the early identification of upper and lower GIB and in the prompt treatment of the haemorrhage.AIM To determine whether a volumetric estimation of the extravasated contrast at CTA in GIB may be a predictor of subsequent positive angiographic findings.METHODS In this retrospective single-centre study,35 patients(22 men;median age 69 years;range 16-92 years)admitted to our institution for active GIB detected at CTA and further submitted to catheter angiography between January 2018 and February 2022 were enrolled.Twenty-three(65.7%)patients underwent endoscopy before CTA.Bleeding volumetry was evaluated in both arterial and venous phases via a semi-automated dedicated software.Bleeding rate was obtained from volume change between the two phases and standardised for unit time.Patients were divided into two groups,according to the angiographic signs and their concordance with CTA.RESULTS Upper bleeding accounted for 42.9%and lower GIB for 57.1%.Mean haemoglobin value at the admission was 7.7 g/dL.A concordance between positive CTA and direct angiographic bleeding signs was found in 19(54.3%)cases.Despite no significant differences in terms of bleeding volume in the arterial phase(0.55 mL vs 0.33 mL,P=0.35),a statistically significant volume increase in the venous phase was identified in the group of patients with positive angiography(2.06 mL vs 0.9 mL,P=0.02).In the latter patient group,a significant increase in bleeding rate was also detected(2.18 mL/min vs 0.19 mL/min,P=0.02).CONCLUSION In GIB of any origin,extravasated contrast volumetric analysis at CTA could be a predictor of positive angiography and may help in avoiding further unnecessary procedures. 展开更多
关键词 Gastrointestinal haemorrhage Computed tomography angiography Volumetric analysis Computer-assisted image interpretation Therapeutic embolization Transcatheter arterial embolization
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A preliminary study on rectal dose reduction associated with hyaluronic acid implantation in brachytherapy for prostate cancer
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作者 Tairo Kashihara Yuka Urago +11 位作者 Hiroyuki Okamoto Mihiro Takemori Hiroki Nakayama Shohei Mikasa Tetsu Nakaichi Kotaro Iijima Takahito Chiba Junichi Kuwahara Satoshi Nakamura Weishan Chang Yoshiyuki Matsui Hiroshi Igaki 《Asian Journal of Urology》 CSCD 2024年第2期286-293,共8页
Objectives: Hydrogel spacer (HS) was developed to reduce rectal toxicities caused by radiotherapy, but has been reported to cause major adverse events. Our institute has attempted to introduce a hyaluronic acid (HA) a... Objectives: Hydrogel spacer (HS) was developed to reduce rectal toxicities caused by radiotherapy, but has been reported to cause major adverse events. Our institute has attempted to introduce a hyaluronic acid (HA) as an alternative spacer. This study aimed to compare rectal doses and geometric distributions between the HS and HA implantation in prostate cancer.Methods: HS and HA were inserted in 20 and 18 patients undergoing high-dose brachytherapy, respectively. The rectum spacer volumes injected were 10 mL and 22 mL, respectively. In the treatment planning system, 13.5 Gy was administered with common catheter positions. The rectal dose indices were assessed between the spacer groups for dosimetry evaluation. Distances between the prostate and rectum and configurations of the spacers were compared.Results: The mean doses irradiated to 0.1 and 2 mL of the rectum were 10.45 Gy and 6.71 Gy for HS, and 6.73 Gy and 4.90 Gy for HA (p<0.001). The mean minimum distances between the prostate and rectum were 1.23 cm and 1.79 cm for HS and HA, respectively (p<0.05). Geometrical configuration comparisons revealed that HA has a higher ability to expand the space than HS.Conclusion: The rectal dose reduction ability of HA is significantly greater than that of HS, suggesting its potential as a new spacer. 展开更多
关键词 BRACHYTHERAPY Hyaluronicacid HYDROGEL Prostaticneoplasm RADIOTHERAPY
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Current status and future perspectives on stem cell transplantation for spinal cord injury
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作者 Edoardo Agosti Marco Zeppieri +4 位作者 Andrea Pagnoni Marco Maria Fontanella Alessandro Fiorindi Tamara Ius Pier Paolo Panciani 《World Journal of Transplantation》 2024年第1期189-209,共21页
BACKGROUND Previous assessments of stem cell therapy for spinal cord injuries(SCI)have encountered challenges and constraints.Current research primarily emphasizes safety in early-phase clinical trials,while systemati... BACKGROUND Previous assessments of stem cell therapy for spinal cord injuries(SCI)have encountered challenges and constraints.Current research primarily emphasizes safety in early-phase clinical trials,while systematic reviews prioritize effectiveness,often overlooking safety and translational feasibility.This situation prompts inquiries regarding the readiness for clinical adoption.AIM To offer an up-to-date systematic literature review of clinical trial results concerning stem cell therapy for SCI.METHODS A systematic search was conducted across major medical databases[PubMed,Embase,Reference Citation Analysis(RCA),and Cochrane Library]up to October 14,2023.The search strategy utilized relevant Medical Subject Heading(MeSH)terms and keywords related to"spinal cord","injury","clinical trials","stem cells","functional outcomes",and"adverse events".Studies included in this review consisted of randomized controlled trials and non-randomized controlled trials reporting on the use of stem cell therapies for the treatment of SCI.RESULTS In a comprehensive review of 66 studies on stem cell therapies for SCI,496 papers were initially identified,with 237 chosen for full-text analysis.Among them,236 were deemed eligible after excluding 170 for various reasons.These studies encompassed 1086 patients with varying SCI levels,with cervical injuries being the most common(42.2%).Bone marrow stem cells were the predominant stem cell type used(71.1%),with various administration methods.Follow-up durations averaged around 84.4 months.The 32.7%of patients showed functional improvement from American spinal injury association Impairment Scale(AIS)A to B,40.8%from AIS A to C,5.3%from AIS A to D,and 2.1%from AIS B to C.Sensory improvements were observed in 30.9%of patients.A relatively small number of adverse events were recorded,including fever(15.1%),headaches(4.3%),muscle tension(3.1%),and dizziness(2.6%),highlighting the potential for SCI recovery with stem cell therapy.CONCLUSION In the realm of SCI treatment,stem cell-based therapies show promise,but clinical trials reveal potential adverse events and limitations,underscoring the need for meticulous optimization of transplantation conditions and parameters,caution against swift clinical implementation,a deeper understanding of SCI pathophysiology,and addressing ethical,tumorigenicity,immunogenicity,and immunotoxicity concerns before gradual and careful adoption in clinical practice. 展开更多
关键词 Spinal cord injury Stem cell therapy Adverse events Functional outcomes Systematic review
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Nodule Detection Using Local Binary Pattern Features to Enhance Diagnostic Decisions
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作者 Umar Rashid Arfan Jaffar +2 位作者 Muhammad Rashid Mohammed S.Alshuhri Sheeraz Akram 《Computers, Materials & Continua》 SCIE EI 2024年第3期3377-3390,共14页
Pulmonary nodules are small, round, or oval-shaped growths on the lungs. They can be benign (noncancerous) or malignant (cancerous). The size of a nodule can range from a few millimeters to a few centimeters in diamet... Pulmonary nodules are small, round, or oval-shaped growths on the lungs. They can be benign (noncancerous) or malignant (cancerous). The size of a nodule can range from a few millimeters to a few centimeters in diameter. Nodules may be found during a chest X-ray or other imaging test for an unrelated health problem. In the proposed methodology pulmonary nodules can be classified into three stages. Firstly, a 2D histogram thresholding technique is used to identify volume segmentation. An ant colony optimization algorithm is used to determine the optimal threshold value. Secondly, geometrical features such as lines, arcs, extended arcs, and ellipses are used to detect oval shapes. Thirdly, Histogram Oriented Surface Normal Vector (HOSNV) feature descriptors can be used to identify nodules of different sizes and shapes by using a scaled and rotation-invariant texture description. Smart nodule classification was performed with the XGBoost classifier. The results are tested and validated using the Lung Image Consortium Database (LICD). The proposed method has a sensitivity of 98.49% for nodules sized 3–30 mm. 展开更多
关键词 Pulmonary nodules SEGMENTATION HISTOGRAM THRESHOLDING
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Functional Confirmation Using a Medical X-Ray System of a Semiconductor Survey Meter
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作者 Katsunao Suzuki Toru Negishi +2 位作者 Yoh Kato Yasuhisa Kono Michiharu Sekimoto 《Open Journal of Radiology》 2024年第1期1-13,共13页
In recent years, semiconductor survey meters have been developed and are in increasing demand worldwide. This study determined if it is possible to use the X-ray system installed in each medical facility to calculate ... In recent years, semiconductor survey meters have been developed and are in increasing demand worldwide. This study determined if it is possible to use the X-ray system installed in each medical facility to calculate the time constant of a semiconductor survey meter and confirm the meter’s function. An additional filter was attached to the medical X-ray system to satisfy the standards of N-60 to N-120, more copper plates were added as needed, and the first and second half-value layers were calculated to enable comparisons of the facility’s X-ray system quality with the N-60 to N-120 quality values. Next, we used a medical X-ray system to measure the leakage dose and calculate the time constant of the survey meter. The functionality of the meter was then checked and compared with the energy characteristics of the meter. The experimental results showed that it was possible to use a medical X-ray system to reproduce the N-60 to N-120 radiation quality values and to calculate the time constant from the measured results, assuming actual leakage dosimetry for that radiation quality. We also found that the calibration factor was equivalent to that of the energy characteristics of the survey meter. 展开更多
关键词 Semiconductor Survey Meter Functional Confirmation Medical X-Ray System Calibration Factor Time Constant
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Using Cross Entropy as a Performance Metric for Quantifying Uncertainty in DNN Image Classifiers: An Application to Classification of Lung Cancer on CT Images
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作者 Eri Matsuyama Masayuki Nishiki +1 位作者 Noriyuki Takahashi Haruyuki Watanabe 《Journal of Biomedical Science and Engineering》 2024年第1期1-12,共12页
Cross entropy is a measure in machine learning and deep learning that assesses the difference between predicted and actual probability distributions. In this study, we propose cross entropy as a performance evaluation... Cross entropy is a measure in machine learning and deep learning that assesses the difference between predicted and actual probability distributions. In this study, we propose cross entropy as a performance evaluation metric for image classifier models and apply it to the CT image classification of lung cancer. A convolutional neural network is employed as the deep neural network (DNN) image classifier, with the residual network (ResNet) 50 chosen as the DNN archi-tecture. The image data used comprise a lung CT image set. Two classification models are built from datasets with varying amounts of data, and lung cancer is categorized into four classes using 10-fold cross-validation. Furthermore, we employ t-distributed stochastic neighbor embedding to visually explain the data distribution after classification. Experimental results demonstrate that cross en-tropy is a highly useful metric for evaluating the reliability of image classifier models. It is noted that for a more comprehensive evaluation of model perfor-mance, combining with other evaluation metrics is considered essential. . 展开更多
关键词 Cross Entropy Performance Metrics DNN Image Classifiers Lung Cancer Prediction Uncertainty
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Contrast Normalization Strategies in Brain Tumor Imaging:From Preprocessing to Classification
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作者 Samar M.Alqhtani Toufique A.Soomro +3 位作者 Faisal Bin Ubaid Ahmed Ali Muhammad Irfan Abdullah A.Asiri 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第8期1539-1562,共24页
Cancer-related to the nervous system and brain tumors is a leading cause of mortality in various countries.Magnetic resonance imaging(MRI)and computed tomography(CT)are utilized to capture brain images.MRI plays a cru... Cancer-related to the nervous system and brain tumors is a leading cause of mortality in various countries.Magnetic resonance imaging(MRI)and computed tomography(CT)are utilized to capture brain images.MRI plays a crucial role in the diagnosis of brain tumors and the examination of other brain disorders.Typically,manual assessment of MRI images by radiologists or experts is performed to identify brain tumors and abnormalities in the early stages for timely intervention.However,early diagnosis of brain tumors is intricate,necessitating the use of computerized methods.This research introduces an innovative approach for the automated segmentation of brain tumors and a framework for classifying different regions of brain tumors.The proposed methods consist of a pipeline with several stages:preprocessing of brain images with noise removal based on Wiener Filtering,enhancing the brain using Principal Component Analysis(PCA)to obtain well-enhanced images,and then segmenting the region of interest using the Fuzzy C-Means(FCM)clustering technique in the third step.The final step involves classification using the Support Vector Machine(SVM)classifier.The classifier is applied to various types of brain tumors,such as meningioma and pituitary tumors,utilizing the Contrast-Enhanced Magnetic Resonance Imaging(CE-MRI)database.The proposed method demonstrates significantly improved contrast and validates the effectiveness of the classification framework,achieving an average sensitivity of 0.974,specificity of 0.976,accuracy of 0.979,and a Dice Score(DSC)of 0.957.Additionally,this method exhibits a shorter processing time of 0.44 s compared to existing approaches.The performance of this method emphasizes its significance when compared to state-of-the-art methods in terms of sensitivity,specificity,accuracy,and DSC.To enhance the method further in the future,it is feasible to standardize the approach by incorporating a set of classifiers to increase the robustness of the brain classification method. 展开更多
关键词 Brain tumor magnetic resonance imaging principal component analysis fuzzy c-clustering support vector machine
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Radiographic Equipment and Accessories as a Potential Source of Nosocomial Infection
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作者 Lina Fahmi Hammad Essam Hussain Mattar +3 位作者 Hanadi Talal Ahmedah Mohamed Zain Shamweel Ahmad Hiba Shamweel 《Open Journal of Radiology》 2024年第3期147-155,共9页
Background: Nosocomial infections have become a major challenge in healthcare facilities as they affect the quality of medical care. Radiological imaging plays a crucial role in medical diagnosis. However, the equipme... Background: Nosocomial infections have become a major challenge in healthcare facilities as they affect the quality of medical care. Radiological imaging plays a crucial role in medical diagnosis. However, the equipment and accessories used increase the risk of transmission of nosocomial bacteria. Objective: This study aims to reveal the extent and nature of microbiological contamination in four hospital diagnostic imaging departments to determine their potential role in the spread of nosocomial bacteria and to evaluate the effectiveness of routine daily disinfection practices in controlling microorganisms in diagnostic imaging departments. Methods & Results: In each department, swabs were taken from the surfaces of selected parts of the equipment and accessories three times a day (early morning, noon, and evening) for five consecutive days. Bacteria were isolated from 65 swabs (36.1% of all samples). The bacteria were isolated 3 times (4.6%) in the morning, 16 times (24.6%) at midday, and 46 times (70.7%) in the evening. The bacteria isolated were Escherichia coli (isolated 34 times;52.3%), Staphylococcus aureus (20 times;30.8%), Staphylococcus epidermidis (6 times;9.3%), and Klebsiella species (5 times;7.7%). Discussion & Conclusion: Findings demonstrated that radiology equipment and accessories are not free of bacteria and further improvements in the sterilization and disinfection of radiology equipment and accessories are needed to protect staff and patients from nosocomial infections. 展开更多
关键词 Diagnostic Imaging Department Nosocomial Infection Radiographic Accessories Radiographic Equipment
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Benefits and drawbacks of radiofrequency ablation via percutaneous or minimally invasive surgery for treating hepatocellular carcinoma
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作者 Ching-Lung Hsieh Cheng-Ming Peng +3 位作者 Chun-Wen Chen Chang-Hsien Liu Chih-Tao Teng Yi-Jui Liu 《World Journal of Gastrointestinal Surgery》 SCIE 2024年第11期3400-3407,共8页
The management of early stage hepatocellular carcinoma(HCC)presents significant challenges.While radiofrequency ablation(RFA)has shown safety and effectiveness in treating HCC,with lower mortality rates and shorter ho... The management of early stage hepatocellular carcinoma(HCC)presents significant challenges.While radiofrequency ablation(RFA)has shown safety and effectiveness in treating HCC,with lower mortality rates and shorter hospital stays,its high recurrence rate remains a significant impediment.Consequently,achieving improved survival solely through RFA is challenging,particularly in retrospective studies with inherent biases.Ultrasound is commonly used for guiding percutaneous RFA,but its low contrast can lead to missed tumors and the risk of HCC recurrence.To enhance the efficiency of ultrasound-guided percutaneous RFA,various techniques such as artificial ascites and contrast-enhanced ultrasound have been developed to facilitate complete tumor ablation.Minimally invasive surgery(MIS)offers advantages over open surgery and has gained traction in various surgical fields.Recent studies suggest that laparoscopic intraoperative RFA(IORFA)may be more effective than percutaneous RFA in terms of survival for HCC patients unsuitable for surgery,highlighting its significance.Therefore,combining MIS-IORFA with these enhanced percutaneous RFA techniques may hold greater significance for HCC treatment using the MIS-IORFA approach.This article reviews liver resection and RFA in HCC treatment,comparing their merits and proposing a trajectory involving their combination in future therapy. 展开更多
关键词 Percutaneous radiofrequency ablation Minimally invasive surgery Hepatocellular carcinoma Intraoperative radiofrequency ablation Contrast-enhanced ultrasound
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2MeV质子辐照对Zr-4合金显微组织的影响 被引量:4
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作者 祖小涛 朱莎 +2 位作者 王鲁闵 尤利平 万发荣 《核动力工程》 EI CAS CSCD 北大核心 2004年第1期50-53,共4页
通过密西根大学离子束表面改性和分析实验室的大束流加速器研究了Zr-4合金的质子辐照效应。结果表明:当原子离位损伤率约1×10-5 dpa/s,在350癈 质子辐照损伤分别达到2dpa、5dpa和7dpa时,辐照后位错环的密度分别为7×1021/m3、8... 通过密西根大学离子束表面改性和分析实验室的大束流加速器研究了Zr-4合金的质子辐照效应。结果表明:当原子离位损伤率约1×10-5 dpa/s,在350癈 质子辐照损伤分别达到2dpa、5dpa和7dpa时,辐照后位错环的密度分别为7×1021/m3、8×1021/m3、15×1021/m3,尺寸分别为7nm、11nm和11nm,表明位错环的密度和尺寸随质子辐照注量有增加的趋势。辐照前后的明场像、高分辨相和电子衍射花样均表明,在350癈 2MeV的质子辐照没有使锆4合金中的hcp-Zr(Cr,Fe)2和fcc-ZrFe2沉淀相发生非晶化转变。 展开更多
关键词 ZR-4合金 质子辐照效应 位错环 透射电镜 显微组织 核动力反应堆 结构材料
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个旧市郊室内氡、钍射气浓度和地面γ辐射水平初步调查 被引量:6
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作者 雷淑洁 Shinji TOKONAMI +7 位作者 孙全富 Tetsuo ISHIKAWA Yosuke KOBAYASHI 李小娟 闵向东 武国亮 Shinji YOSHINAGA 尚兵 《中国职业医学》 CAS 北大核心 2008年第3期211-213,共3页
目的调查个旧地区居室内氡(^222Rn)、钍射气(^220Rn)及其子体水平,明确钍射气的剂量贡献。方法考虑住宅类型和地理分布因素,从个旧市郊某村选取建筑结构有代表性的50户住宅的主卧室,采用氡-钍射气鉴别探测器测量氡、钍射气浓度... 目的调查个旧地区居室内氡(^222Rn)、钍射气(^220Rn)及其子体水平,明确钍射气的剂量贡献。方法考虑住宅类型和地理分布因素,从个旧市郊某村选取建筑结构有代表性的50户住宅的主卧室,采用氡-钍射气鉴别探测器测量氡、钍射气浓度,用沉积率装置测量钍射气子体浓度。其中14间居室采用连续性氡测量探测器和α谱氡、钍射气鉴别探测器测量氡、钍射气浓度,空气采样滤膜结合CR-39探测器测量钍射气衰变产物浓度,碘化钠闪烁计数器测量地表γ剂量率。结果50间居室的氡浓度为32~498Bq/m^3,平均136Bq/m^3;钍射气浓度为39~7908Bq/m^3,平均3297Bq/m^3;钍射气子体浓度为2.0~23.9Bq/m^3,平均10.2Bq/m^3。钍射气子体衰变产物致居民年平均有效剂量大于氡子体衰变产物的平均年有效剂量(2.9mSv vs 1.6mSv)。结论个旧市郊部分居室室内钍射气及其子体浓度高,钍射气子体的剂量贡献要高于氡子体的剂量贡献。在个旧开展氡致肺癌危险评价研究应当考虑钍射气子体的剂量贡献。 展开更多
关键词 钍射气 钍射气子体 Γ射线 个旧市
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英文版主观认知下降问卷21的汉化研究 被引量:7
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作者 郝立晓 邢悦 +1 位作者 贾建国 韩璎 《中国全科医学》 CAS 北大核心 2021年第18期2349-2354,共6页
背景主观认知下降(SCD)是阿尔茨海默病(AD)患者的早期表现之一,其早期简易筛查工具的研发有利于帮助临床早期识别AD,但部分轻度认知障碍(MCI)患者主观认知下降问卷9(SCD-Q9)为0分,可能与该问卷未涵盖所有SCD主诉有关。目的对筛选出SCD-Q... 背景主观认知下降(SCD)是阿尔茨海默病(AD)患者的早期表现之一,其早期简易筛查工具的研发有利于帮助临床早期识别AD,但部分轻度认知障碍(MCI)患者主观认知下降问卷9(SCD-Q9)为0分,可能与该问卷未涵盖所有SCD主诉有关。目的对筛选出SCD-Q9的上位条目池即主观认知下降问卷21(SCD-Q21)进行汉化,找出可识别SCD风险的SCD主诉条目并进一步优化SCD-Q9。方法2020-07-01至2020-08-31,参考国外问卷本土化标准程序,经原作者授权、同意后获得英文版原版问卷,采用Brislin“两人直译·回译”法对SCD-Q21进行汉化,并通过专家小组讨论及小样本预调查进行条目修订及文化调适。结果本研究经严格的翻译、回译、对比回译、条目修订、文化调适及小样本预调查而形成中文版SCD-Q21终稿。中文版SCD-Q21终稿由21个条目组成,其中条目4、5、7、10、20、21为三分类选项,其余均为二分类选项;条目11、19为反向条目,其余均为正向条目;总分21分。结论中文版SCD-Q21终稿的形成为后续该问卷在中国人群中的运用奠定了坚实基础,也为AD早期简易筛查工具的探索提供了一种方法。 展开更多
关键词 阿尔茨海默病 主观认知下降 筛查 主观认知下降问卷
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重离子辐照诱发TiNiCu合金非晶化的原位电子显微研究 被引量:5
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作者 祖小涛 朱莎 +1 位作者 张传飞 王鲁闽 《材料研究学报》 EI CAS CSCD 北大核心 2003年第2期210-213,共4页
在美国Argonne国家实验室连接有IVEM-Tandem National Facility加速器的Hi-tatch3000电子显微镜上,通过400KeV Xe^+离子就位辐照研究了TiNiCu形状记忆合金的常温晶态-非晶态转变。入射的Xe离子通过级联碰撞,从0.05 dpa开始辐照诱发TiNiC... 在美国Argonne国家实验室连接有IVEM-Tandem National Facility加速器的Hi-tatch3000电子显微镜上,通过400KeV Xe^+离子就位辐照研究了TiNiCu形状记忆合金的常温晶态-非晶态转变。入射的Xe离子通过级联碰撞,从0.05 dpa开始辐照诱发TiNiCu合金化学无序,非晶化过程和化学无序几乎同时进行;0.2dpa后,马氏体变体的衬度明显减小,变得非常模糊;在0.4dpa非晶化转变完成,马氏体变体的衬度完全消失。 展开更多
关键词 金属材料 TINICU形状记忆合金 重离子辐照 原位电子显微镜 非晶化 钛镍铜合金
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东海和冲绳沉积物中自生铀蓄积过程及控制机理 被引量:2
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作者 王中良 刘丛强 +1 位作者 朱兆洲 山田正俊 《地球化学》 CAS CSCD 北大核心 2006年第3期240-248,共9页
采用同位素稀释ICP-MS测定法,对中国东海陆架及日本冲绳海槽的6个沉积物芯中U和Th的同位素地球化学行为进行了研究,以了解氧化还原敏感元素U在近海次氧化性沉积物中的蓄积行为,并评价其在全球海洋铀平衡中的意义。东海沉积物芯中,238U... 采用同位素稀释ICP-MS测定法,对中国东海陆架及日本冲绳海槽的6个沉积物芯中U和Th的同位素地球化学行为进行了研究,以了解氧化还原敏感元素U在近海次氧化性沉积物中的蓄积行为,并评价其在全球海洋铀平衡中的意义。东海沉积物芯中,238U浓度及238U/232Th比值随深度变化不明显。但是在冲绳海槽沉积物芯中,238U浓度及238U/232Th比值在沉积芯表层氧化带显示较低值,然后在次氧化层随深度增加而增加。230Th和232Th浓度在所有沉积物芯中基本不随深度变化。这些结果说明,冲绳沉积物中有“自生铀”的蓄积过程发生,蓄积速率约为(47±5)~(90±8)ng/(cm2·a),与文献报道的世界其他海域次氧化性沉积区大致相当。进一步证明了U在近海次氧化性沉积区的蓄积对于全球海洋铀平衡有重要意义。“自生铀”的主要蓄积机制是海水U(Ⅵ)向沉积物迁移,在还原条件下被还原为惰性的U(Ⅳ)并被吸附在沉积物固体相上。 展开更多
关键词 自生铀 氧化还原 沉积物 蓄积速率 东海 冲绳海槽
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310℃和350℃下锆-4合金中沉淀相非晶化研究 被引量:2
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作者 祖小涛 孙凯 +1 位作者 尤力平 王鲁闽 《强激光与粒子束》 EI CAS CSCD 北大核心 2005年第2期287-290,共4页
用大束流加速器和透射电子显微镜研究了Zr 4合金在310 ℃和350 ℃下的质子辐照效应。当质子能量为2 MeV,在 310 ℃和 350 ℃下质子辐照产生原子离位损伤达 5 dpa(注量率为 8.5×1013 cm-2 ·s-1),辐照前后的明场像、高分辨相和... 用大束流加速器和透射电子显微镜研究了Zr 4合金在310 ℃和350 ℃下的质子辐照效应。当质子能量为2 MeV,在 310 ℃和 350 ℃下质子辐照产生原子离位损伤达 5 dpa(注量率为 8.5×1013 cm-2 ·s-1),辐照前后的明场像、高分辨相和电子衍射花样均表明:在310 ℃辐照产生原子损伤达到 5 dpa,沉淀相 Zr(Cr,Fe)2 边缘5~10 nm的区域已经非晶化,而在350 ℃时质子辐照却没有非晶化发生。沉淀相 Zr(Cr,Fe)2的元素分布图像和浓度分布表明,铁元素向基体扩散并且聚集在非晶化边界区域。 展开更多
关键词 锆-4合金 质子辐照效应 非晶化 透射电镜 元素分布 原子离位损伤
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高剂量离子注入直接形成Ge纳米晶的物理机理 被引量:1
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作者 胡强 卢铁城 +5 位作者 敦少博 张松宝 唐彬 代君龙 朱莎 王鲁闽 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第8期1543-1548,共6页
研究了单束双能高剂量Ge离子注入、不经过退火在非晶态SiO2薄膜中直接形成镶嵌结构Ge纳米晶的物理机制.实验中利用不加磁分析器的离子注入机,采用Ge弧光放电离化自动形成的Ge^+和Ge^2+双电荷离子并存的单束双能离子注入方法,制备了... 研究了单束双能高剂量Ge离子注入、不经过退火在非晶态SiO2薄膜中直接形成镶嵌结构Ge纳米晶的物理机制.实验中利用不加磁分析器的离子注入机,采用Ge弧光放电离化自动形成的Ge^+和Ge^2+双电荷离子并存的单束双能离子注入方法,制备了10^16~10^18cm^-2多种剂量Ge离子注入的Si基SiO2薄膜样品.用GIXRD表征了Ge纳米晶的存在,并仔细分析得到了纳米晶形成的阈值剂量.通过TEM分析了Ge纳米晶的深度分布和晶粒尺寸.用SRIM程序分别计算了双能离子在SiO2非晶层的射程和深度分布,与实验结合,得到纳米晶形成的物理机制,即纳米晶的形成与单束双能离子注入时Ge^+和Ge^2+相互碰撞产生的能量沉积在SiO2中形成的局域高温有关. 展开更多
关键词 Ge纳米晶 阈值剂量 单束双能离子注入
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固体气泡探测器-固体核径迹探测器的新类别 被引量:1
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作者 郭士伦 Doke T +9 位作者 李丽 陈宝流 张东海 Kikuchi J Terasawa K Komiyama M Hara K Fuse T Yasuda N Murakami T 《核技术》 EI CAS CSCD 北大核心 2005年第9期659-662,共4页
利用高能重离子p、He、C、Si、Ar、Fe、Kr和Xe对固体气泡探测器的性质进行了研究。结果表明,固体气泡探测器具有许多与固体核径迹探测器相似的性质,且具有显影主动性、实时记录性、体径迹显示能力等多方面普通固体核径迹探测器所不具有... 利用高能重离子p、He、C、Si、Ar、Fe、Kr和Xe对固体气泡探测器的性质进行了研究。结果表明,固体气泡探测器具有许多与固体核径迹探测器相似的性质,且具有显影主动性、实时记录性、体径迹显示能力等多方面普通固体核径迹探测器所不具有的性能。可以得出结论:固体气泡探测器是固体核径迹探测器的一种新类别。 展开更多
关键词 固体气泡探测器 固体核径迹探测器 高能重离子探测
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固体气泡损伤探测器阈起源的实验判别 被引量:1
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作者 郭士伦 李丽 +5 位作者 Doke T Kikuchi J Terasawa K Hara K Sakuma N Yasuda N Murakami T 《核技术》 CAS CSCD 北大核心 2002年第7期506-510,共5页
用 5 0 0MeV/u56Fe,6 5 0MeV/u40Ar ,6 0 0MeV/u2 8Si和 180MeV/u4He对固体气泡损伤探测器 (T- 12型 )进行了实验研究 ,实验结果表明 ,固体气泡损伤探测器的阈特性可用临界能量损失率表征。在一般条件下 ,限定能量损失率在不同重离子产... 用 5 0 0MeV/u56Fe,6 5 0MeV/u40Ar ,6 0 0MeV/u2 8Si和 180MeV/u4He对固体气泡损伤探测器 (T- 12型 )进行了实验研究 ,实验结果表明 ,固体气泡损伤探测器的阈特性可用临界能量损失率表征。在一般条件下 ,限定能量损失率在不同重离子产生径迹时不具有相同临界值 ,因此 。 展开更多
关键词 固体气泡损伤探测器 阈起源 临界能量损失率 限定能量损失率
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