Relationships between Radiation Dose and Chromosome Aberrations Induced by Heavy Ions in Human P
GB50484--石化施工安全规范
石油化工建设工程施工安全技术规范GB 50484 2008 自2009 年6 月1 日起实施本规范是根据建设部《2005 年工程建设标准规范制订、修订计划(第二批）的通知》(建标函[2005]124 号）,由中国石油化工集团公司组织编制。
规范内容共分10 章，包括总则、术语、施工安全管理通用规定、临时用电、起重作业、脚手架作业、土建作业、安装作业、施工检测、施工机械使用。
1.0.1 为适应石油化工建设工程的需要,保障人身安全和健康,保护公众财产不受损失，保护环境不受危害,制定本规范。
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0.2 本规范适用于石油炼制、石油化工、化纤、化肥等建设工程施工的安全技术管理.1。
0.3 石油化工工程建设施工必须坚持“安全第一，预防为主”的方针。
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4 石油化工建设工程施工安全技术除应执行本规范外，尚应符合国家现行有关标准的规定。
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1 施工用火 hot work 石油化工工程建设中各类金属焊接、切割作业及其他产生火花和明火作业统称为施工用火.2。
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2 固定动火区 specified hot work area 在石油化工建设工程项目施工现场限定的范围内，不需要办理动火作业证即可进行动火作业的区域.2。
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3 生命绳 life yarn 高处作业中专门用来悬挂安全带的绳索。
2.0.4 临时用电 electricity on construction site 为建设工程项目施工提供的、工程施工完毕即行拆除的电力线路与电气设施。
2.0.5 配电柜 distributing tank 布置在施工配电室（包括独立配电房和箱式变电站)内的配电装置，包括进线柜和出线柜。
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0.6 总配电箱 total distribution box 布置在用电负荷中心的落地式配电装置，其进线端与配电室的出线柜相连，出线端与分配电箱或大功率用电设备相连.2.0。
7 分配电箱 sub-distribution box 分布在各施工点，使用电设备就近获得电源的配电装置,其进线端与总配电箱相连，出线端与开关箱或用电设备相连。
术前256层螺旋CT双低剂量扫描对结肠癌肿瘤侵犯及肠系膜血管分布的评估价值
学术论著中国医学装备2023年6月第20卷第6期 China Medical Equipment 2023 June V ol.20 No.6[文章编号] 1672-8270(2023)06-0047-06 [中图分类号] R816.5 R735.3+5 [文献标识码] AAssessment value of preoperative 256-slice spiral CT double-low-dose scan in the tumor invasion and the distribution of mesenteric blood vessels of colon cancer/XUAN Jian-xin, LIU Zhe-feng, TENG Wei, et al//China Medical Equipment,2023,20(6):47-52.[Abstract] Objective: T o explore the assessment value of preoperative 256-slice spiral computed tomography (CT) double low-dose scanning in assessing the tumor invasion and the distribution of mesenteric blood vessels of colon cancer. Methods: A total of 140 patients who were scheduled to undergo laparoscopic radical resection of colon cancer in Chengde Central Hospital were selected and they were divided into a double-low-dose group and a conventional-dose group by random number table method, with 70 cases in each group. Both the double-low-dose group and the conventional-dose group underwent 256-slice spiral CT double-low-dose and conventional-dose scans before operation. The objective and subjective evaluations of image qualities and radiation dose were compared between the two groups, and the diagnostic results of postoperative histopathology were used as the "gold standard" to analyze the accuracies of conventional dose CT and double-low-dose CT in assessing the tumor invasion and the distribution of mesenteric blood vessel of colon cancer. Results: The signal to noise ratio (SNR), contrast to noise ratio (CNR), noise and CT values of the double-low-dose group were significantly lower than those of the conventional dose group (t =14.415, t =16.045, t =2.163, t =30.096, P <0.05), respectively. The image quality scores of 2 physicians in the double-low-dose group were slightly lower than those in the conventional dose group, but there was no significant difference between the two groups. The dose length product (DLP), computed tomography dose index (CTDI vol ) and the effective dose (ED) in the double-low-dose group were significantly lower than those in the conventional-dose group (t =20.227, t =21.355, t =24.207, P <0.05), respectively. The accuracies of double-low-dose CT in assessing lymph node metastasis, vascular invasion, and nerve invasion [86.21%(25/29), 85.71%(18/21), 94.44%(17/18)] were not significantly different with those of postoperative pathology, respectively. The accuracies of double-low-dose CT in assessing the tissue of superior mesenteric vein, arterial distribution on the dorsal side of the superior mesenteric vein, and arterial distribution on the ventral side of the superior mesenteric vein respectively were 98.57%(68/70), 90.32%(28/31) and 94.59% (35/37), which were no significant differences with those of postoperative pathology. Conclusion: Preoperative 256-slice spiral CT double-low-dose scan of colon cancer can improve image quality, which has obvious advantages in reducing radiation dose and image noise, and it can accurately assess preoperative the tumor invasion and the distribution of mesenteric blood vessels for colon cancer. [Key words] Colon cancer; 256-slice spiral computed tomography (CT); Low dose; T umor invasion; Distribution of mesenteric blood vessel[First-author’s address] Department of Radiology, Chengde Central Hospital, Chengde 067000, China.[摘要] 目的：探究术前256层螺旋CT双低剂量扫描对结肠癌肿瘤侵犯及肠系膜血管分布的评估价值。
专题05 阅读理解D篇(2024年新课标I卷) (专家评价+三年真题+满分策略+多维变式) 原卷版
《2024年高考英语新课标卷真题深度解析与考后提升》专题05阅读理解D篇（新课标I卷）原卷版(专家评价+全文翻译+三年真题+词汇变式+满分策略+话题变式)目录一、原题呈现P2二、答案解析P3三、专家评价P3四、全文翻译P3五、词汇变式P4(一)考纲词汇词形转换P4(二)考纲词汇识词知意P4(三)高频短语积少成多P5(四)阅读理解单句填空变式P5(五)长难句分析P6六、三年真题P7(一)2023年新课标I卷阅读理解D篇P7(二)2022年新课标I卷阅读理解D篇P8(三)2021年新课标I卷阅读理解D篇P9七、满分策略（阅读理解说明文）P10八、阅读理解变式P12 变式一：生物多样性研究、发现、进展6篇P12变式二：阅读理解D篇35题变式（科普研究建议类）6篇P20一原题呈现阅读理解D篇关键词: 说明文;人与社会;社会科学研究方法研究;生物多样性; 科学探究精神;科学素养In the race to document the species on Earth before they go extinct, researchers and citizen scientists have collected billions of records. Today, most records of biodiversity are often in the form of photos, videos, and other digital records. Though they are useful for detecting shifts in the number and variety of species in an area, a new Stanford study has found that this type of record is not perfect.“With the rise of technology it is easy for people to make observation s of different species with the aid of a mobile application,” said Barnabas Daru, who is lead author of the study and assistant professor of biology in the Stanford School of Humanities and Sciences. “These observations now outnumber the primary data that comes from physical specimens(标本), and since we are increasingly using observational data to investigate how species are responding to global change, I wanted to know: Are they usable?”Using a global dataset of 1.9 billion records of plants, insects, birds, and animals, Daru and his team tested how well these data represent actual global biodiversity patterns.“We were particularly interested in exploring the aspects of sampling that tend to bias (使有偏差) data, like the greater likelihood of a citizen scientist to take a picture of a flowering plant instead of the grass right next to it,” said Daru.Their study revealed that the large number of observation-only records did not lead to better global coverage. Moreover, these data are biased and favor certain regions, time periods, and species. This makes sense because the people who get observational biodiversity data on mobile devices are often citizen scientists recording their encounters with species in areas nearby. These data are also biased toward certain species with attractive or eye-catching features.What can we do with the imperfect datasets of biodiversity?“Quite a lot,” Daru explained. “Biodiversity apps can use our study results to inform users of oversampled areas and lead them to places – and even species – that are not w ell-sampled. To improve the quality of observational data, biodiversity apps can also encourage users to have an expert confirm the identification of their uploaded image.”32. What do we know about the records of species collected now?A. They are becoming outdated.B. They are mostly in electronic form.C. They are limited in number.D. They are used for public exhibition.33. What does Daru’s study focus on?A. Threatened species.B. Physical specimens.C. Observational data.D. Mobile applications.34. What has led to the biases according to the study?A. Mistakes in data analysis.B. Poor quality of uploaded pictures.C. Improper way of sampling.D. Unreliable data collection devices.35. What is Daru’s suggestion for biodiversity apps?A. Review data from certain areas.B. Hire experts to check the records.C. Confirm the identity of the users.D. Give guidance to citizen scientists.二答案解析三专家评价考查关键能力，促进思维品质发展2024年高考英语全国卷继续加强内容和形式创新，优化试题设问角度和方式，增强试题的开放性和灵活性，引导学生进行独立思考和判断，培养逻辑思维能力、批判思维能力和创新思维能力。
dose用法
dose用法用法及详解：dose1. 名词用法•(1) 量度单位：Dose作为名词时，可表示一定量的药物、辐射等。
常见搭配有：– A dose of medicine: 一剂药物– A high/low dose: 高/低剂量–The recommended dose: 建议剂量•(2) 服用药量：Dose也可以指代医学中的药物服用量，常见短语有：–Take a dose: 服一次剂量–Miss a dose: 错过服药时间–Overdose: 药物过量•(3) 放射剂量：在核能或医学测试中，Dose表示辐射剂量。
常见表达方式有：–Radiation dose: 辐射剂量–High/low dose radiation: 高/低剂量辐射•(4) 动物毒药或毒素：在动物学或毒理学中，Dose可指代动物或生物摄入的毒药或毒素量。
表达常用词组有：–Toxic dose: 毒性剂量–Lethal dose: 致死剂量–LD50 (Lethal Dose 50%): 致死50%剂量2. 动词用法•(1) 给予药物：Dose可以作为动词，意为给予某人或某物药物剂量。
常见用法有：–Dose (someone/something) with (medicine): 给予某人/某物某种药物剂量–He was dosed with antibiotics: 他服用了抗生素•(2) 注射剂量：在医学或实验环境中，Dose也可以指示对某人或某物注射特定剂量。
常见表达方式有：–Dose (someone/something) with (a vaccine): 对某人/某物注射疫苗–The mice were dosed with a chemical: 小鼠被注射了一种化学物质•(3) 加药：在化学合成或实验中，Dose可以指示向某个溶液或混合物中加入特定剂量的药物。
常用短语包括：–Dose (a solution) with (a chemical): 向某溶液中加入一种化学物质–The reaction was dosed with a catalyst: 反应中添加了催化剂3. 其他用法•(1) 音乐用语：在音乐领域，Dose用于描述音乐的节奏或旋律的部分。
放射医学专业英语翻译
Unit 4 Section ADNA Strand Breaks and Chromosomal Abberations Inducedby Ionizing Radiation（1）1.What is the principal target for the biologic effects of radiation on the basis of strong circumstantial evidence?基于详细的证据，辐射生物效应的主要靶点是什么？2. What is the structure of a deoxyribonucleic acid molecule?脱氧核糖核酸分子的结构是什么?DNA Strand BreaksDNA链断裂There is strong circumstantial evidence to indicate that deoxyribonucleic acid (DNA) is the principal target for the biologic effects of radiation, including cell killing mutation, and carcinogenesis. A consideration of the biologic effects of radiation therefore must begin logically with a description of the breaks in DNA caused by charged-particle tracks and by the chemical species produced.有足够多且详细的证据表明脱氧核糖核酸是辐射生物效应的主要的靶，包括细胞杀伤性突变和致癌作用。
因此，从带电粒子和化学产物导致的DNA链断裂来考虑辐射生物效应是较合乎逻辑的。
俯卧腹板固定技术在直肠癌术前放疗摆位中的重复性分析
俯卧腹板固定技术在直肠癌术前放疗摆位中的重复性分析李扬成;何振宇;刘慧;貌友兄【摘要】目的探讨俯卧腹板固定技术在直肠癌术前放疗摆位中的重复性和精确性.方法50例直肠癌术前放疗患者随机分成真空袋组和俯卧腹板组各25例,在治疗前、治疗中每周及治疗结束当天均拍摄射野验证片以了解摆位的重复性,并比较两组之间及每周之间的差异.结果俯卧腹板组和真空袋组相比射野中心点的偏差在X、Y和Z方向上均无统计学差异(P＞0.05);而在放疗中每周及放疗结束时的比较中,俯卧腹板组射野中心点的偏差在X、Y和Z方向上无显著差异(P＞0.05),但真空袋组射野中心点的偏差在X、Y和Z方向存在显著差异(P＜0.05).结论与常规真空袋固定技术相比较,俯卧腹板固定技术有相似的重复性,并且受时间的影响较少,建议临床上进一步研究.【期刊名称】《岭南现代临床外科》【年(卷),期】2010(010)005【总页数】3页(P332-334)【关键词】直肠癌;放疗;体位固定;腹板【作者】李扬成;何振宇;刘慧;貌友兄【作者单位】510060,广东广州,华南肿瘤学国家重点实验室;510060,广东广州,中山大学肿瘤防治中心放疗科;510060,广东广州,华南肿瘤学国家重点实验室;510060,广东广州,中山大学肿瘤防治中心放疗科;510060,广东广州,华南肿瘤学国家重点实验室;510060,广东广州,中山大学肿瘤防治中心放疗科;510060,广东广州,华南肿瘤学国家重点实验室;510060,广东广州,中山大学肿瘤防治中心放疗科【正文语种】中文【中图分类】R735.3近10年来，术前放疗在局部晚期直肠癌综合治疗中地位越来越重要，研究表明术前同期放化疗能显著提高局部控制率及延长患者的远期生存率［1，2］。
但放疗可造成盆腔器官放射性损伤，特别是小肠。
目前通常采用俯卧位、充盈膀胱等方法来降低小肠受照剂量［3，4］。
本研究通过在直肠癌术前放疗中采用俯卧腹板固定技术，并与常规真空袋固定技术比较，探讨俯卧腹板固定技术在直肠癌术前放疗摆位中的重复性。
迭代算法(Asir-V)在儿童胸部扫描中的应用价值
迭代算法(Asir-V)在儿童胸部扫描中的应用价值董丽娜【摘要】目的探讨Asir-V技术在儿童胸部低剂量扫描中的应用价值.方法对60例患儿根据Asir-V的设置随机分为3组,每组20例,Asir-V分别为30%、50%和70%.每例分别测量胸廓入口层面,气管分叉层面,心底层面背部肌肉CT值的标准差(Standard Deviation,SD)为背景噪声指数,记录每个病例的剂量长度乘积(Dose-Length Product,DLP),并根据公式换算有效剂量,比较3组SD和有效剂量(Effective Dose,ED)值.结果 3组病例SD分别为21.74±1.39、21.42±1.67和22.07±1.99,DLP分别为(18.99±9.55)、(12.77±4.22)和(7.45±2.01)mGy·cm,ED 分别为(0.57±0.21)、(0.34±0.10)和(0.20±0.05)mSv,3组SD值相当,任意两组差异(P>0.05)无统计学意义,ED递减,任意两组差异(P<0.01)有统计学意义.读片结果各病例图像质量良好(≥3分),两位医师图片一致性良好.结论 Asir-V技术在保证图像质量的同时,可有效降低辐射剂量,对儿童胸部低剂量扫描有重要价值.%Objective To explore the application value of Asir-V technology in low dose chest scanning in children. Methods Sixty cases were randomly divided into three groups (20 in each group) based on different algorithms: group A (Asir-V: 30%), group B (Asir-V: 50%), group C (Asir-V, 70%). The SD of muscle of back in thoracic inlet level, trachea bifurcation level and the bottom of heart level were used as the background noise index. The dose length product of each case was recorded, and the effective dose was calculated according to the formula. The SD and ED values were compared among the 3 groups. Results The SD values in the three groups were21.74±1.39, 21.42±1.67 and 22.07±1.99, respect ively. The DLP values were(18.99±9.55), (12.77±4.22) and (7.45±2.01) mGy·cm. ED values were (0.57±0.21), (0.34±0.10) and (0.20±0.05) mSv, respectively. There were no significant difference between any two groups for SD value (P>0.05). However, there were significant differences for ED value in any two groups (P<0.01). Conclusion Asir-V technology is not only ensure the quality of the image, but also effectively reduce the radiation dose. So it has great value for low dose scanning in children's chest.【期刊名称】《中国医疗设备》【年(卷),期】2018(033)001【总页数】4页(P69-71,81)【关键词】迭代算法;滤波反投影法;小儿胸部;低剂量;多层螺旋CT【作者】董丽娜【作者单位】徐州市儿童医院医学影像科,江苏徐州 221000【正文语种】中文【中图分类】R814.42引言儿童呼吸系统疾病为最常见的疾病之一，胸部CT检查作为儿童胸片的补充手段被广泛应用。
1例特殊疾病背景的出血性痔病例报告及文献回顾
Journal of Colorectal &Anal Surgery结直肠肛门外科2021年4月第27卷第2期1例特殊疾病背景的出血性痔病例报告及文献回顾黄丹丹，张迪，彭慧，任东林△中山大学附属第六医院肛肠外科广东广州510655DOI:10.19668/ki.issn1674-0491.2021.02.005出血性痔是临床常见的肛肠疾病之一，常采用保守治疗和手术治疗（包括痔切除术、套扎术、注射术等），可获得良好的治疗效果。
然而，当出血性痔合并特殊疾病时，往往会给临床医师制定治疗决策带来巨大的挑战和困难。
本文通过回顾1例特殊疾病背景的出血性痔患者的治疗过程，详细分析该患者的病史、诊断、治疗及预后，为临床医师开展痔病规范化诊疗提供参考。
1临床资料患者男性，67岁，因“反复便血7月余，加重2月”于2019年7月17日到我院就诊。
患者自诉于7月余前无明显诱因下出现排粪疼痛，伴少量便血，5月余前在当地医院诊断为“1.直肠低分化腺癌T 2N 1M 0Ⅲ期；2.前列腺癌未排？”。
随后转至上级医院就诊，因患者拒绝手术故行30次放疗及4疗程化疗。
近两个月出现便后出血加重，以滴血、喷血多见，伴头晕、心悸、肛门疼痛等症状。
1周前于外院就诊，血常规结果提示：血红蛋白63g/L ，血小板66×109/L ，予输血、降压、护心、局部压迫止血等对症支持治疗，便后出血症状改善不明显，遂转诊我院。
既往史：患者自诉10余年前诊断“混合痔”，未予处理；高血压病史20余年，测量血压最高值为200/120mmHg ，规律服用降压药，血压控制良好。
就诊前测得血压值偏低，患者停用降压药1周；冠心病10余年，规律服用降脂及抗血小板聚集药物，已停用1周。
入院体格检查：腹部视诊未见异常，全腹无压痛、反跳痛，肠鸣音正常。
肛周皮肤无溢液，因放疗呈花斑样改变（见图1），肛门未见痔核脱出，无触痛。
指诊肛门括约肌紧张，触痛明显，肛管狭窄，直肠黏膜粗糙，未扪及异常肿物，退出指套血染。
辐射外文翻译 中英文
本外文翻译含中英文，前面英文，后面中文。
Mobile Phone Radiation Induces Reactive OxygenSpecies Production and DNA Damage in HumanSpermatozoa In VitroAbstractBackgroundIn recent times there has been some controversy over the impact of electromagnetic radiation on human health. The significance of mobile phone radiation on male reproduction is a key element of this debate since several studies have suggested a relationship between mobile phone use and semen quality. The potential mechanisms involved have not been established, however, human spermatozoa are known to be particularly vulnerable to oxidative stress by virtue of the abundant availability of substrates for free radical attack and the lack of cytoplasmic space to accommodate antioxidant enzymes. Moreover, the induction of oxidative stress in these cells not only perturbs their capacity for fertilization but also contributes to sperm DNA damage. The latter has, in turn, been linked with poor fertility, an increased incidence of miscarriage and morbidity in the offspring, including childhood cancer. In light of these associations, we have analyzed the influence of RF-EMR on the cell biology of human spermatozoa in vitro.Principal FindingsPurified human spermatozoa were exposed to radio-frequency electromagnetic radiation (RF-EMR) tuned to 1.8 GHz and covering a range of specific absorption rates (SAR) from 0.4 W/kg to 27.5 W/kg. In step with increasing SAR, motility and vitality were significantly reduced after RF-EMR exposure, while the mitochondrial generation of reactive oxygen species and DNA fragmentation were significantly elevated (P<0.001). Furthermore, we also observed highly significant relationships between SAR, the oxidative DNA damage bio-marker, 8-OH-dG, and DNA fragmentation after RF-EMR exposureConclusionsRF-EMR in both the power density and frequency range of mobile phones enhances mitochondrial reactive oxygen species generation by human spermatozoa, decreasing the motility and vitality of these cells while stimulating DNA base adduct formation and, ultimately DNA fragmentation. These findings have clear implications for the safety of extensive mobile phone use by males of reproductive age, potentially affecting both their fertility and the health and wellbeing of their offspringlistIntroduction (1)Results (2)RF-EMR disrupts human sperm motility and vitality and induces intracellular reactive oxygen species (ROS) production (2)RF-EMR has a negative impact on human spermatozoa over a range of SAR values (4)Reactive Oxygen Species are central to the RF-EMR response (5)RF-EMR induces oxidative DNA damage (8-OH-dG) (6)RF-EMR induces DNA fragmentation in human spermatozoa (7)Discussion (9)Methods (12)Ethics Statement (12)Reagents and Solutions (12)Human spermatozoa (12)Radio Frequency Electromagnetic Radiation and Waveguide (13)Dihydroethidium Assay (14)MitoSOX Red (MSR) Assay (15)Assay for 8-hydroxy-2′-deoxyguanosine (8-OH-dG) (15)TUNEL Assay (16)Analysis by Flow Cytometry (16)Statistics (17)References (17)IntroductionMale infertility is a distressingly common condition affecting about 1 in 20 of the male population [1]. In a majority of cases, the male partner produces sufficient numbers of spermatozoa to achieve fertilization but there are functional defects in these cells that prevent conception from occurring [2]. Despite several decades of research, the causes of such functional deficiencies in human spermatozoa remain largely unresolved. However, one contributory factor that has recently emerged is the quality of the sperm DNA delivered to the oocyte at the moment of fertilization [3]. Fragmentation of DNA in the male germ line has been associated with impaired fertilization, poor embryonic development, high rates of miscarriage and an increased incidence of morbidity in the offspring, including childhood cancer [3], [4]. In view of the seriousness of these clinical outcomes, attention has recently focused on the environmental and genetic factors that might be involved in the aetiology of DNA damage in the male germ line.These investigations have suggested that one of the environmental factors potentially involved in the etiology of DNA damage in human spermatozoa is an increased exposure to radio-frequency electromagnetic radiation (RF-EMR) emitted from mobile phones. This association was initially suggested by an epidemiological study which found negative correlations between mobile phone usage and various attributes of semen quality, particularly motility [5]. This was immediately followed by an experimental study involving exposure of male mice to RF-EMR, which revealed a significant impact on the integrity of both the mitochondrial and nuclear genomes [6]. Recently, the negative impact of mobile phone usage on semen quality in human males was confirmed in a study that found the duration of exposure to be correlated with defects in sperm count, motility, viability, and normal morphology [7]. In light of these data, there is now an urgent need to determine whether exposure of human spermatozoa to RF-EMR can also induce DNA damage and to resolve the cellular mechanisms involved.Several studies have found an association between human health and exposure to RF-EMR, with emphasis on a range of clinical conditions including childhood leukaemia, brain tumours, genotoxicity and neurodegenerative disease [8], [9]. While the cellular mechanisms underpinning these effects have not been completely resolved, it has been suggested that oxidative stress could be a key factor [10]. However, extensive analysis of the importance of oxidative stress in mediating the pathological effects of RF-EMR has generated conflicting results, possibly due to differences in the fundamental redox susceptibility of the cell lines employed in these analyses [11]. In this context, it is significant that human spermatozoa are uniquely sensitive to oxidative stress for a variety of reasons. Firstly, these cells arelargely devoid of the cytoplasm that in somatic cells houses the antioxidant enzymes that offer a first line of defense against free radical attack [12]. Secondly, these cells possess abundant targets for the induction of peroxidative damage including polyunsaturated fatty acids and DNA [12]–[14]. Thirdly, these cells are professional generators of reactive oxygen species, that appear to emanate largely from the sperm mitochondria and, possibly, plasma membrane NAD(P)H oxidases [15], [16]. Thus if any cell type would be vulnerable to the oxidative stress reportedly generated on exposure to RF-EMR, it would be human spermatozoa.In light of these considerations, we have conducted a careful analysis of the biological consequences of exposing human spermatozoa to RF-EMR. The study design involved overnight exposure to RF-EMR at a defined frequency (1.8 GHz), over a range of SAR values that both covered the emission characteristics of mobile phones and generated sufficient dose-response data to shed light on the underlying pathophysiological mechanisms. Moreover, the temperature of the incubations was maintained at 21°C to avoid any secondary heating effects. The results clearly demonstrate that exposure to this type of radiation not only stimulates free radical generation by the sperm mitochondria but also creates a state of oxidative stress characterized by the formation of oxidative base adducts and DNA fragmentation. These data clearly have important implications for the safety of mobile phone use and highlight the potential importance of RF-EMR in the etiology of male infertility and childhood disease.ResultsRF-EMR disrupts human sperm motility and vitality and induces intracellular reactive oxygen species (ROS) productionIn an initial experiment, functional human spermatozoa isolated from the high density region of Percoll gradients and suspended in BWW medium were exposed to RF-EMR at an SAR of 27.5 W/kg. This exposure induced a highly significant decline in both vitality (p<0.001; Figure 1A) and motility (p<0.01; Figure 1B) compared with the unexposed controls. Exposed spermatozoa also produced significantly higher amounts of ROS than background levels as measured by both the dihydroethidium (DHE) (p<0.001; Figure 1C) and MitoSOX red (MSR) probes (p<0.001; Figure 1D) suggesting that free radical generation had been initiated as a consequence of RF-EMR and that the mitochondria were significantly involved in this response.Figure 1. RF-EMR exposure decreases motility and vitality of human sperm while also inducing intracellular ROS.Percoll-purified spermatozoa (5×106 cells) were suspended in 1 ml BWW in a 35 mm Petri dish and placed within the waveguide while control cells placed outside the waveguide. A frequency of 1.8 GHz at a SAR of 27.5 W/kg was used and all samples were incubated for 16 h at 21°C. A, Sperm vitality was significantly reduced from the control value of 82%±4% to 29%±4% for the exposed cells (***p<0.001). B, Sperm motility was also significantly reduced from the control value of 82%±4% to 28%±1% (**p<0.01). C, ROS production was increased after RF-EMR exposure such that 28%±1% of the cells were producing ROS, while only 7%±0.4% of the controls contributed to ROS production (***p<0.001). D, 24%±1% of the exposed cells generated mitochondrial ROS, while the only 12%±1% of the control cells produced ROS from this source (***p<0.001). All results are based on 4 independent samples. doi:10.1371/journal.pone.0006446.g001RF-EMR has a negative impact on human spermatozoa overa range of SAR valuesIn light of these results we then extended the range of SAR values over which the consequences of RF-EMR radiation were examined (0.4 W/kg–27.5 W/kg) to include the values covered by conventional mobile phones (0.5 W/kg–1.5 W/kg).High quality spermatozoa selected in discontinuous Percoll gradients displayed a decline in both vitality and motility after exposure to RF-EMR in a dose- dependent manner. The control populations maintained an average vitality of 89%; however, significant reductions in vitality were observed at exposure levels as low as 1.0 W/kg (p<0.01) (Figure 2A). Similarly, the control populations maintained motilities at an average of 86% over the incubation period, however after exposure to RF-EMR at levels of 1.0 W/kg, motility was observed to significantly decrease to 68% (p<0.05) and decreased still further at higher SAR exposures (Figure 2B).Figure 2. RF-EMR exposure reduces motility and vitality of human spermatozoa, in an SAR dependent manner.Percoll-purified spermatozoa (5×106 cells) were suspended in 1 ml BWW in a 35 mm Petri dish and placed within the waveguide while control cells (closed circles) were placed outside the waveguide. Cells in the waveguide were exposed to 1.8 GHz RF-EMR at SAR levels of 0.4, 1.0 2.84.3 10.1 and 27.5 W/kg (open circles) for 16 h at 21°C. Both vitality and motility were reduced ina dose dependent manner. A, Vitality was significantly reduced at a SAR of 1.0 W/kg from 89%±3% to 65%±1% (**p<0.01). B, Motility was also significantly reduced at a SAR of 1.0 W/kg from 86%±2% to 68%±2% (*p<0.05). All results are based on 4 independent samples.doi:10.1371/journal.pone.0006446.g002Reactive Oxygen Species are central to the RF-EMR response Exposure of human spermatozoa to RF-EMR over a range of SAR levels resulted in a dose-dependent activation of ROS generation, as detected by the DHE probe (Figure 3A). In this analysis, a significant increase in ROS positive cells was observed after exposure at 1.0 W/kg (p<0.05); thereafter ROS production rose rapidly with SAR values up to 4.3 W/kg and then began to plateau reaching a peak of 30% at the highest exposure levels assessed (Figure 3A). To determine whether such increases in ROS production might originate from the sperm mitochondria, MSR was employed as a probe. Spermatozoa exposed to increasing levels of RF-EMR, generated a significant, dose-dependent increase in ROS generation by the mitochondria. The response rose rapidly following RF-EMR exposure reaching statistical significance (p<0.001) at an SAR value 2.8 W/kg at which point 16% of the exposed cells were MSR positive. At SAR values above 4.3 W/kg, RF-EMR induced mitochondrial ROS begun to plateau reaching 30% at the maximal SAR values assessed (Figure 3B). By plotting the DHE positive cells against the MSR response for the entire data set (Figure 3D) we observed an extremely strong correlation (R2 = 0.823) between these signals, suggesting that a majority of the ROS production elicited by RF-EMR involved electron leakage from the mitochondrial electron transport chain.Figure 3. RF-EMR induces ROS generation in human spermatozoa, in an SAR-dependent manner unrelated to thermal effects.Percoll-purified spermatozoa (5×106 cells) were suspended in 1 ml BWW in a 35 mm Petri dish and placed within the waveguide while control cells placed outside the waveguide (closed circles). Cells in the waveguide were exposed to 1.8 GHz RF-EMR at SAR levels between 0.4 and 27.5 W/kg (open circles) for 16 h at 21°C. Also, purified sperm cells were subjected to incubation temperatures ranging from 21°C–50°C for 2 h. As the power levels were increased, the cellular generation of ROS increased in a dose-dependent manner. ROS levels were also observed to increase as a result of incubation temperature, but such results were not significant until the temperature exceeded 40°C. A, ROS generation (DHE response) was significantly increased from control levels after exposure to 1.0 W/kg (*p<0.05) and above (***p<0.001). B, RF-EMR induces ROS generation by the sperm mitochondria as monitored by MSR; significant increases were observed at SAR values of 2.8 W/kg (***p<0.001) and above. All results are based on 4 independent samples. C, In order to control for thermal effects, the impact of temperature of cellular ROS generation was monitored; a significant increase in ROS generation was observed as temperatures rose above 40°C (p<0.001). D, Across the entire data set, the total level of ROS generation by human spermatozoa (DHE positive cells) was highly correlated with the level of ROS generation by the mitochondria (MSR positive cells: R2 = 0.823).doi:10.1371/journal.pone.0006446.g003In order to control for bulk thermal effects of RF-EMR exposure, spermatozoa were also incubated at temperatures ranging from 21°C–50°C for 2 h (Figure 3C). This analysis did reveal an effect of heat on free radical generation by human spermatozoa possibly due to the activation of an apoptotic response, however these effects were only significant above 40°C. Thus at the temperature at which these experiments were performed (21°C) the highest observed RF-EMR-induced temperature rise (+0.4°C at 27.5 W/kg), could not of itself account for the increased ROS response observed across the range of SAR settings evaluated in this study.RF-EMR induces oxidative DNA damage (8-OH-dG)In order to determine whether the ROS generation induced on exposure of human spermatozoa to RF-EMR resulted in a state of oxidative stress, we monitored the expression of8-hydroxy-2′-deoxyguanosine (8-OH-dG), a marker for oxidative damage to sperm DNA. As the SAR level was increased, the amount of oxidative DNA damage expressed in the spermatozoa became elevated (Figure 4A). A significant increase in 8-OH-dG expression became apparent at low SAR values (<5.0 W/kg) rising to a maximum of around 20% at the highest levels of exposure (27.5 W/kg). By plotting the 8-OH-dG positive cells against the MSR signal (Figure 4B) it was apparent that a strong positive correlation existed between the two parameters (R2 = 0.727); thehigher the level of mitochondrial ROS generation, the greater the degree of oxidative DNA damage in the spermatozoa.Figure 4. RF-EMR induces oxidative DNA damage in human spermatozoa.Following Percoll fractionation, 5×106 high density, spermatozoa were suspended in 1 ml BWW. The cells were placed in 35 mm Petri dishes and placed inside a waveguide. 5×106 cells in 1 ml BWW were placed outside the waveguide as a control (closed circle). The cells in the waveguide were exposed to 1.8 GHz RF-EMR at SAR levels between 0.4 and 27.5 W/kg (open circles) and all samples were incubated for 16 h at 21°C. Following incubation, Fe2+ and H2O2 was added to cells to act as a positive control, incubated for 1 h, then 100 µl 2 mM DTT/BWW solution was added and incubated for 45 min at 37°C. Cells were fixed and labeled with 100 µl charcoal purified anti-8-OH-dG, FITC tagged antibody at a dilution of 1:50, incubated at 21°C for 1 h, washed and then assessed by flow cytometry. A, As the power levels were increased, the amount of oxidative DNA damage expressed also increased. A significant amount of oxidative DNA damage was observed in cells exposed to 2.8 W/kg (*p<0.05) RF-EMR and above (**p<0.01; ***p<0.001). Results are based on 4 independent samples. B, The levels of 8-OH-dG expression were positively correlated with the levels of ROS generation by the mitochondria (R2 = 0.727).doi:10.1371/journal.pone.0006446.g004RF-EMR induces DNA fragmentation in human spermatozoa To determine whether the oxidative DNA base damage precipitated by RF-EMR-induced ROS generation had any impact on DNA stand breaks in human spermatozoa, the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was utilized. As illustrated in Figure 5A, human spermatozoa responded to RF-EMR exposure, with a significant increase in DNA strand breaks atan SAR of 2.8 W/kg (p<0.05) that increased rapidly with rising SAR values and then reached a plateau so that at the highest SAR level assessed (27.5 W/kg), 29% of the cells expressed significant DNA fragmentation. This DNA damage was highly correlated with free radical generation by the sperm mitochondria giving a correlation coefficient of R2 = 0.861 (Figure 5B). Moreover, the level of DNA fragmentation was highly correlated with 8-OH-dG formation (R2 = 0.725; Figure 5C) such that sperm cells exhibiting high levels of oxidative DNA damage, also possessed high levels of DNA fragmentation.Figure 5. RF-EMR induces DNA fragmentation in human spermatozoa.Following Percoll fractionation, 5×106 high density spermatozoa were resuspended in 1 ml BWW, pipetted into 35 mm Petri dishes and placed inside a waveguide. 5×106 cells in 1 ml BWW were placed outside the waveguide as a control (closed circle). The cells in the waveguide were exposed to 1.8 GHz RF-EMR at SAR levels between 0.4 and 27.5 W/kg (open circles) and all samples were incubated for 16 h at 21°C. Following incubation, cells were fixed; DNase-I was used as a positive control. After 1 h incubation at 37°C, 50 µl of label and enzyme master mixes were added to the cells and incubated for 1 h at 37°C. Cells were then washed and assessed by flow cytometry. A, Significant levels of DNA fragmentation was observed in exposed spermatozoa at 2.8 W/kg (*p<0.05) and above (***p<0.001). B, DNA fragmentation was positively correlated with ROS production by the mitochondria as monitored by MSR (R2 = 0.861). C, 8-OH-dG was also positively correlated with DNA fragmentation (R2 = 0.725). Results are based on 4 independent samples.doi:10.1371/journal.pone.0006446.g005DiscussionWhile a high proportion of the male population suffers from infertility associated with defective sperm function [17], the etiology of this condition remains largely unresolved. Notwithstanding the general paucity of information in this area, recent studies have highlighted the interesting finding that male infertility patients are frequently characterized by high levels of DNA damage to their spermatozoa [18]. In light of these data, we have hypothesized that the disruption of sperm fertilizing potential and the concomitant presence of high levels of DNA damage in the sperm nucleus involves a common causative mechanism in the form of oxidative stress [19].Oxidative stress has been known for some time to limit the fertilizing potential of human spermatozoa through the induction of peroxidative damage to the sperm plasma membrane [13], [20]. Oxidative stress is also known to be associated with DNA damage in human spermatozoa [21]. Furthermore, the source of the free radicals responsible for generating such stress appears to be the mitochondria [15]. However, the factors responsible for inducing the mitochondria to leak electrons and propagate the production of ROS have not been elucidated. The research described in this article suggests that one of the key environmental factors involved in the stimulation of sperm mitochondria to produce high levels of ROS, might be excess exposure to RF-EMR from sources such as mobile phones.In a pilot study, human spermatozoa were found to respond to RF-EMR (at 1.8 GHzwith a SAR of 27.5 W/kg) with a range of negative changes including dramatic declines in both sperm vitality and motility. We also observed significant increases in both cytoplasmic ROS levels (DHE) as well as mitochondrial ROS levels (MSR) after RF-EMR exposure. We have previously shown that the chemical induction of mitochondrial ROS production with rotenone can precipitate a state of oxidative stress leading to high levels of lipid peroxidation and a loss of sperm motility [15]. Therefore, these data highlight the particular vulnerability of human spermatozoa to oxidative attack and the potential significance of sperm mitochondria in the generation of free radicals.To assess whether similar effects could be observed at lower power densities, closer to the SAR values associated with mobile phones (0.5–1.5 W/kg) a dose-dependent analysis was conducted. In addition to the conventional assessments of motility and vitality, assays were included to assess the potential for RF-EMR to induce sperm DNA damage and further, whether the DNA damage was oxidative in nature. Confirmation of the detrimental effects of RF-EMR on human sperm was again observed. Over the power density range employed, a significant (P<0.001) dose-dependent response for all sperm parameters was observed, including motility, vitality, ROS generation by the whole cell, ROS generation by the mitochondria, oxidative DNA damage and DNA fragmentation. Furthermore, the profiles of all the observed effects with respect to SAR were intriguingly similar, suggesting a common underlying mechanism.Specifically, all of the responses examined showed an extremely rapid change at low SAR exposures that then reached a plateau at a point where around 30% of the sperm population was affected. This suggests that while we were careful to use only Percoll-purified, high quality spermatozoa in this analysis, there exists within this cell population, a cohort of spermatozoa that are particularly vulnerable to the induction of oxidative stress by RF-EMR. These spermatozoa may have compromised mitochondria, poorly remodeled chromatin or a combination of such factors [15], [22]. Heterogeneity within the sperm population is a feature of the human condition. However, this does not mean that a majority of spermatozoa would not, ultimately, be affected by RF-EMR in vivo; much would depend on the duration of exposure. In vitro, we are limited by the inability of human spermatozoa to survive for more than 24 hours in a simple defined culture medium. In vivo, spermatozoa may take up to a week to move from the seminiferous tubules in the testes to the cauda epididymis and during the whole of this time they would be vulnerable to RF-EMR exposure [23].We recognize that these studies were conducted using spermatozoa suspended in a simple defined culture medium rather than the epididymal plasma in which they would be suspended in vivo. Nevertheless the fact that effects on sperm quality havepreviously been observed in both whole animal radiation experiments [3] and in epidemiological studies of human subjects exposed to various levels of mobile phone radiation [5], [7], [24], emphasizes the biological and clinical relevance of these findings. Moreover, another recent study has found that exposing human spermatozoa to mobile phone radiation for 1 hour leads to significant declines in motility and vitality in concert with an increase in cellular reactive oxygen species generation [25]. The levels of RFEMR exposure were not quantified in this study nor were the sources of ROS identified. Nevertheless, these findings reinforce the general conclusions generated in this paper, particularly with respect to central role played by oxidative stress. The ever-increasing prevalence of mobile communications technology means that humans are now exposed to higher amounts of RF-EMR than ever before. Mobile phones are commonly carried in bags or in pockets in very close proximity to the body. In addition to this, these devices can be stored adjacent to the same part of the body for extended periods of time. In this context, exposure of the male reproductive system to RF-EMR is clearly a significant issue.The particular significance of the present study is that it not only demonstrates a direct effect of RF-EMR on sperm motility, vitality and DNA integrity but also identifies a potential causative mechanism involving electron leakage from the mitochondrial electron transport chain and the induction of oxidative DNA damage. In part, these mechanistic insights have been achieved because the cell type used in these studies, the human spermatozoon, has an extremely simple cellular architecture, lacking significant cytosol and possessing few cellular organelles other than the sperm nucleus, flagellum and mitochondria. One consequence of this structure is that these cells are uniquely vulnerable to oxidative stress. Moreover, such stress is already known to induce the functional and structural lesions observed in this study including both a loss of motility mediated by peroxidative damage to the sperm plasma membrane, as well as the formation of DNA base adducts in the sperm nucleus that ultimately lead to DNA fragmentation [26], [27].Notwithstanding the specialized nature of mammalian spermatozoa, the mechanisms suggested by this study may also apply to RF-EMR-mediated damage in other cell types. The RF-EMR used for communications, including mobile phone networks, is not of high enough power to be classed as ionizing radiation. The latter has sufficient energy to pull away electrons, dramatically altering the properties of affected molecules and typically creating extremely reactive radical species. RF-EMR does not contain sufficient energy for these processes. Nevertheless, this form of radiation may have other effects on larger scale systems such as cells and organelles, which stem from the perturbation of charged molecules and the disruption of electron flow [28], [29]. Mitochondria have one of the largest standing membrane potentials in the body and their energetic functions are entirely dependent on the regulated movement of electrons and protons within the inner mitochondrion membrane.Theoretically, such fluxes might be susceptible to disruptions in local electric fields induced by RF-EMR, offering a potential link between this form of radiation and the non-thermal biological effects observed in this study.This study clearly demonstrates that RF-EMR can damage sperm function via mechanisms that involve the leakage of electrons from the mitochondria and the creation of oxidative stress. These findings have immediate implications for the high rates of male infertility seen in our species, a majority of which is idiopathic. Furthermore, the fact that sperm DNA is damaged by this form of radiation has additional implications for the health and wellbeing of children born to fathers who have experienced high levels of occupational or environmental exposure to RF-EMR around the time of conception. Overall, these finding raise a number of related health policy and patient management issues that deserve our immediate attention. Specifically we recommend that men of reproductive age who engage in high levels of mobile phone use, do not keep their phones in receiving mode below waist level.MethodsEthics StatementThis study was conducted according to the principles expressed in the Declaration of Helsinki. The study was approved by the University of Newcastle (H-712-0799). All patients provided written informed consent for the collection of samples and subsequent analysis.Reagents and SolutionsAll chemicals and reagents used in this research were obtained from Sigma Aldrich (Sigma Chemical Co., St. Louis, MO) unless stated otherwise. All reagents used were of research grade. All fluorescent probes were purchased from Molecular Probes Inc. (Eugene, OR). Biggers, Whitten and Whittingham (BWW) media supplemented with 1 mg/ml polyvinyl alcohol (PVA) was used in all experiments [30]. It was prepared fresh as required and kept at 37°C with an osmolarity in the range of 290–310 mOsm/kg. Human spermatozoaInstitutional and State Government ethical approval was secured for the use of。
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原本打算每人交一篇论文，但估计一部分同学会网上下载，凑数，所以，我们考试就是词汇，范围包括下面我列出来的和课后的，只要能根据英语写出汉语即可。
下周上课时间我们简单考一下，请大家复习一下。
第一课element（元素）, fundamental particles（基本粒子），protons, neutrons and electrons（质子，中子，电子），chemical identity（化学特性），nucleus （原子核），positively charged （带正电的），uncharged（不带电的），negatively charged （带负电的），electrically neutral（电中性的），atomic number（原子序数），Periodic Table（元素周期表），mass number（质量数），nucleon（核子），carbon（碳），orbital electrons（轨道电子），innermost electron（内壳层电子），naturally occurring（天然存在的），stable isotope（稳定同位素），unstable （不稳定的）or radioactive（放射性的），artificial means（人工手段），chemical bonds（化学键），nuclei（原子核nucleus的复数），chemical symbol（化学符号）, subscript（下角标），superscript （上角标），oxygen（氧），radioactive isotopes（放射性同位素），Hydrogen（氢），nuclear engineering（核工程），heavy hydrogen（重氢）or deuterium（氘），tritium（氚）mass and charge（质量和电荷）, atomic and nuclear physics（原子和原子核物理），atomic mass unit (u)（原子质量单位），one twelfth （十二分之一）carbon 12 （碳12），weighted mean （加权平均数），Avogadro’s Number（阿伏加德罗常数），compounds and molecules（化合物和分子），equal in magnitude and opposite in sign（数量相等，符号相反），electron-volt（电子伏特），mega electron-volt（兆电子伏特）( MeV)，unit electronic charge（单位电荷），potential difference （势差），classical principle（经典原理），conservation of mass（质量守恒定律），mass defect （质量亏损），principle of the equivalence of mass and energy（质能相当原理），interchange of mass and energy（质能转换），laws of conservation of mass and conservation of energy（质量守恒和能量守恒定律），release of energy（能量的释放）, absorption of energy（能量的吸收），equivalence between mass and energy（质能相当），force of electrostatic repulsion between like charge（同种电荷之间的静电排斥力）, force of attraction（吸引力），nuclear force（核力），nucleon（核子），Binding Energy（结合能），energy of chemical binding（化学结合能），Energy Level（能级），ground state of energy（能量基态），nuclear reaction （核反应），excited states or levels （激发态或激发能级），discrete excited states （分立的激发态），spacing of the levels （能级间隔），excitation energy （激发能），average lifetime （平均寿命），decay, or become de-excited（衰变或退激发），emission of high energy electromagnetic radiation （发射高能电磁辐射），fission （裂变），uranium （铀），transuranium elements（超铀元素），radioactive barium 139（放射性钡139），split into fragments （分裂成碎片），intermediate mass elements （中间质量的元素），medium mass number（中等质量数）, chain reaction （链式反应）uranium 235（铀235）, Thorium 232（钍232）, fissionable （可裂变的）, fissile（易裂变的），uranium 233 and plutonium 239（钚239）, low energy neutrons（低能中子），liquid drop model（液滴模型），short range nuclear forces（短程核力）, surface tension （表面张力）, action of the nuclear forces（核力作用），dumbbell shape （哑铃形），Coulomb force of repulsion （库仑排斥力），emission of gamma radiation（发射伽玛辐射），fission fragments （裂变碎片），neutrinos （中微子），macroscopic（宏观的）第二课radiation（辐射），material or electromagnetic origin（物质或电磁起源）, nuclear decay（核衰变），particle accelerator（粒子加速器）, cosmic rays（宇宙射线）, molecules, atoms, electrons, and nuclei（分子，原子，电子，原子核），photons（光子），target（靶），projectile （入射粒子），nuclear energy field（核能领域），nuclear reactor（核反应堆）, inert substances（惰性物质），protective shielding（防护屏），Excitation and Ionization （电离和激发），fluorescent light bulb（荧光灯泡）, vacuum tube （真空管），impart energy to （传递能量），excitation of electrons to higher energy states（激发电子到更高能态），emission of light（发光）.inner orbits （内层轨道），high energy radiation（高能辐射），heavy element target（重元素靶，X-rays due to transitions in the electronic orbits（电子在轨道间跃迁产生的X射线）, bremsstrahlung （韧致辐射），ion pair（离子对），range（射程）, millimeter（毫米），meter （米），Charged particles（带电粒子），fragments of fission （裂变碎片），heavy particles （重离子）, inertia（惯性），electrostatic interaction （静电相互作用），kinetic energy （动能），inversely proportional to（成反比例），million-electron-volt （百万电子伏特）high-speed charged ion （高速带电离子），mutual repulsion （相互排斥），hyperbolic path （双曲线轨迹），scatter（散射），initial energy （初始能量），scattering of the photon（光散射）, ionization by the photon（光电离）, pair production（电子对产生）. Photon-Electron Scattering（光-电子散射），rest mass （静止质量），bound to their nucleus（受原子核的束缚）, free stationary particles（自由静止粒子），physical principles of energy and momentum conservation（能量和动量守恒物理原理. Compton effect（康普顿效应）, scattered backward（背散射），the special theory of relativity （狭义相对论），cross section（截面），Photoelectric Effect（光电效应），incident photon （入射光子），light emission （发光）, Electron-Positron Pair Production（电子正电子对产生），be converted into matter（转变成物质），theory of the equivalence of mass and energy（质能相当理论），law of conservation of charge （电荷守恒定律），be annihilated as material particles（作为物质粒子湮灭）, substance（物质）, attenuation of gamma rays in matter （伽马射线在物质中的衰减），mean free path （平均自由程）,helium 4 （氦4），positive charge（正电荷），density of the material （物质密度），aluminum （铝），health hazard （健康危害），alpha-emitting isotope（α放射性同位素），be ingested in the body(摄入人体)，radioactive isotope（放射性同位素），a spectrum of energies（能谱），ingestion hazard（摄入危害）. penetrating power（穿透本领），radiation hazards （辐射危害），reactor shielding（反应堆屏蔽）.light elements （轻元素），beryllium（铍），Neutron（中子），average lifetime （平均寿命），Neutron Source（中子源），radium 226（镭226），potential scattering （势散射），compound nucleus formation（复合核形成），capture（俘获）。