125I示踪法研究rhPTH(1～34)在大鼠体内的药代动力学

采用125I标记重组人甲状旁腺素（1～34）肽（Recombinant Human Parathyroid hormone（1～34），rhPTH（1～34））示踪技术，研究rhPTH(1～34)在SD大鼠体内的药代动力学。结果显示，SD大鼠单次皮下给予1.8和3.6μg/kg剂量的rhPTH1-34后，其主要药代动力学参数为：达峰时间Tmax为0.26±0.07 h和0.25±0.0 h，血浆峰浓度为1.30±0.17 μg/L和3.20±1.12μg/L，末端消除半衰期T1/2el为1.70±0.56 h和1.58±0.70 h，药物浓度－时间曲线下面积AUC(0-∞)为3.1±0.7 μg•h /L和6.7±0.7 μg•h /L。表明大鼠单次皮下给予rhPTH(1～34)后，在给药后大约0.25 h血药浓度达到峰值，随后出现一个较快的消除过程，其药代动力学特征符合非静脉给药线性一房室模型一级动力学。     

塞来昔布对大鼠急性放射性脑损伤的保护作用

为探讨塞来昔布对电离辐射诱发的急性脑组织损伤的脑保护作用,将成熟的SD大鼠随机分为对照组、照射组(6 MeV电子线全脑单次垂直照射,吸收剂量为10 Gy)和照射加药物组(6 MeV电子线全脑单次垂直照射,吸收剂量为10 Gy+塞来昔布30 mg/kg体重灌胃给药)。实验大鼠分别在不同时间点处死、取脑组织。应用干-湿重法测定脑组织含水量,病理切片观察大鼠脑组织形态变化,免疫组化法观察脑组织中胶质纤维酸性蛋白(GFAP)的表达。结果显示:与对照组相比,SD大鼠照射后脑组织含水量明显升高,照射加药物组大鼠各时间点脑组织含水量较照射组显著减少,差异有统计学意义(P<0.05)。全脑照射后,照射组大鼠脑组织切片呈现典型脑水肿表现,照射加药物组脑水肿程度较照射组轻。照射加药物组大鼠各时间点脑组织中GFAP阳性细胞的数量较照射组显著减少,差异有统计学意义(P<0.05),两组全脑照射后大鼠脑组织中GFAP阳性表达均较对照组明显升高。塞来昔布能有效地降低脑组织含水量,减轻脑组织水肿的程度,保护脑组织,并能减轻胶质细胞的损伤程度,起到保护神经元的作用。     

SD大鼠放射性直肠炎模型的建立

采用X射线单次大剂量局部照射的方法,对SD大鼠进行不同剂量的照射,通过观察照射后大鼠的临床症状和组织病理学改变,探讨大鼠放射性直肠炎模型的建立方法。结果表明,X射线大剂量单次局部照射 18 Gy能成功诱导大鼠急性放射性直肠炎,该模型适合用于放射性直肠损伤药物治疗效果研究的需要。     

土壤中钚的迁移行为研究

我国表层土壤中存在的钚主要来自于20世纪中后叶大气层核试验之后的全球沉降。本研究以土壤中现存的钚为研究对象,利用加速器质谱(AMS)和电感耦合等离子体质谱(ICP-MS)对环境中痕量水平钚同位素精准测量技术,在我国部分典型地区进行了现场土壤纵向分层采样和实验室测量。在此基础之上,将对流-弥散方程在单次瞬时输入情况下的解与我国不同地区土壤柱中钚核素的垂直分布数据进行了拟合,得到新疆、湖北、贵州、重庆、甘肃土壤中钚核素的表观对流系数为0.046~0.163 cm/a,表观扩散系数为0.058~0.339 cm2/a,土壤中239+240Pu浓度峰的迁移速率为0.063~0.187 cm/a。实测结果表明,钚同位素在土壤中的迁移速率与土壤有机质含量有明确的负相关关系。     

大鼠尿液中γ辐射损伤特征代谢物

目的：探讨γ辐射对大鼠尿液代谢物的影响,初步筛选与γ辐射损伤密切相关的特征尿代谢物。方法采用核磁共振技术对60 Coγ射线单次照射（剂量率0．7 Gy/min ,剂量6．0 Gy ）后不同时间点（照射前1天及照射后第1、2、3、4、8、18、30、45天）和分次照射后不同累积剂量点（剂量率18 mGy/min ,累积剂量分别为0、0．2、0．4、0．6、0．8、1．0 Gy ）大鼠尿液的代谢成分进行检测。主成分分析法（PCA ）和偏最小二乘法（PLS-DA ）分析检测数据。筛选单次照射和分次照射所致辐射损伤的共同特征代谢物。结果单次照射后,大鼠尿牛磺酸、脯氨酸相对含量在照后第1～45天持续偏高;分次照射后,尿牛磺酸、脯氨酸相对含量均有随剂量增加而增加的趋势。结论γ辐射可导致大鼠长期代谢紊乱。尿牛磺酸、脯氨酸相对含量与照射剂量有相关性,可作为γ辐射损伤的特征代谢物。     

在出生前以氚水照射致大鼠脑发育障碍的剂量效应关系研究

以脑组织中游离氨基酸含量为指标,观察出生前因氚水照射引起的大鼠脑发育障碍。实验用妊娠11d的大鼠经腹腔单次注入7.4×10~3—3.7×10~6Bq/ml(体水)放射性浓度的氚水。在仔鼠出生后18d将其开颅取出大脑。取一半脑组织用高效液相色谱(HPLC)测定脑组织中游离氨基酸含量。结果表明:受照仔鼠大脑组织中游离氨基酸含量随照射剂量增加而增多。在仔鼠总吸收剂量为0.0038—1.9Gy范围内,大脑组织中游离氨基酸含量增加的百分率与剂量对数值之间可拟合成直线回归方程Y=A+B lgD。     

25MeVX射线束照射的离体人血中淋巴细胞微核率的剂量-效应关系

本文报告了用 Shimedzu BTR-25型医用感应电子加速器的25MeVX 线照射离体人血,诱发淋巴细胞微核率的剂量-效应关系。结果表明,微核细胞率和微核率与照射剂最可拟配合呈直线方程 Y=a+bD。     

全脑全脊髓放疗中静态调强和容积调强的剂量学对比

回顾性选取2019年在我院放疗中心接受全脑全脊髓照射(CSI)的病人20例,勾画靶区和危及器官(OAR)后,传输至Oncentra 4.1治疗计划系统,对全脑全脊髓放疗采用静态调强(ss-IMRT)和容积调强(VMAT)两种放疗技术进行计划,分别计算两种技术的适形指数(CI)、均匀指数(HI)、107%处方剂量线所包含的靶区体积(V₁₀₇)、靶区内最大剂量点剂量值(D_max)、危及器官受量、正常组织(NT)受量、机器跳数和治疗时间并进行比较,比较两种调强方法的剂量学差异。结果表明,采用VMAT技术,靶区覆盖度、CI、HI、V₁₀₇、D_max、OAR受照量等参数优于ss-IMRT技术,治疗时间和机器跳数也明显减少。但靶区外正常组织(NT)低剂量的辐射区域增大。说明在CSI中,VAMT优于ss-IMRT 具有优势,但接受CSI患者大多是儿童,低剂量的辐射区域是否增加不良反应及其对临床影响有待于进一步研究。     

电子直线加速器上位机控制软件开发

使用LabView开发出一套电子直线加速器上位机控制软件包,它包括本地监控软件、远程监控软件。 本地监控软件实现了对加速器各子系统数据采集、状态显示、故障分析、时序的可视化等的监视功能,操作控制功能包括对待机、启动、出束、复位的控制,以及参数的调整(包括脉冲调制器系统的参数、出束参数、AFC参数),同时进行实时的数据库存储,将加速器的运行数据按每秒5次的速率存储到数据库中,并可实现不同速率的回放,便于诊断。     

低压条件下气态UF6纯度的红外光谱分析方法

为建立低压条件下使用傅立叶红外光谱法定量分析气态UF₆的纯度方法，本研究选取1 150 cm^-1处的吸收峰作为定量分析UF₆纯度时的特征吸收峰。针对UF₆气体净化后尾料中UF₆残留量的在线分析需求，建立满足真空密封要求的红外分析系统、标准样品配比系统和背景图谱标定装置，对不同纯度、不同压力条件下的气态UF₆标准样品进行分析，建立UF₆纯度与其特征吸收峰面积、稳定压力相关的计算公式。结果表明，通过该方法可准确地得到60～140 Pa的压力范围内和0～100%的纯度范围内气态UF₆的纯度。建立的分析方法和计算公式满足低压条件下UF₆气体在线快速分析的要求。     

Comparison of near threshold fatigue crack growth data by Kmax-constant method with the post-construction codes

In this paper we obtain near threshold fatigue crack growth (FCG) data for several carbon steels and type 304 stainless steel by the K_max-constant method. Since the FCG rate obtained by the K_max-constant method is considered to give the upper limit of the FCG data obtained by the stress ratio-constant method, this data was compared with the FCG evaluation diagrams given in the ASME and Japan Society of Mechanical Engineers (JSME) pressure vessel post-construction codes to ensure their validity. Though the FCG rate for carbon steel S55C was somewhat affected by the K_max value, the results show that the obtained near threshold FCG data is close to the upper bound of the JSME code diagram, which is an extrapolation of the ASME FCG diagram to the near threshold region.     

Line width of single-crystal Mössbauer absorption

The Mössbauer line broadening method for the determination of Lamb–Mössbauer factors f_LM cannot be applied directly in the determination of the probability of the resonant absorption f_LM for single-crystalline absorbers with quadrupole splitted Mössbauer spectra. The line width Γ_exp for single crystals with quadrupole splitted Mössbauer spectra has been computed for various absorber thicknesses. The polarization effects are important and have been taken into account. The linear dependence has been adapted for Lamb–Mössbauer factor measurements by introducing a polarization-dependent coefficient. This method has been tested on measurements of guanidinium nitroprusside (GNP) (CN₃H₆)₂[Fe(CN)₅NO] single crystals.     

Transient Nonlinear Response of Plastic Scintillators

The peak dose rate for which light output is linearly proportional to incident radiation intensity was measured by bombarding 80-mil-thick samples of NE 102 and MEL 150C scintillators with 12-MeV electrons from the EG&G/AEC linear accelerator. To obtain the equivalent gamma dose rate, the sensitivity of the scintillator-photodiode detector used in this work was measured with a calibrated Co60 source. Nonlinear behavior was observed for excitation pulse widths between six nanoseconds and 0.5 microseconds. Analysis of the detector signals indicates that nonlinearity is a function of total dose as well as dose rate. Thus for an excitation pulse width of 0.5 microseconds, scintillator output was found to be linear at the start of the burst, but showed marked nonlinearity by the end of the pulse. The data also indicate that if the dose rate drops below the threshold value after a scintillator is driven into nonlinear operation, the scintillator will continue to behave nonlinearily for some time. The decay time associated with recovery from nonlinearity is greater than 0.5 microsecond. Data are presented, showing the average dose rate required to produce 5% and 10% nonlinear behavior as a function of exposure time. As a typical case, 10% nonlinear behavior for NE 102 results from an average dose rate of 6.5 × 1011 R/sec for an exposure time of 10 nanoseconds.     

用LiF-TLD测量脉冲电子加速器的轫致辐射场

本文给出用 LiF 热释光探测器(以下简称 LiF-TLD)对某脉冲电子加速器(厚靶)轫致辐射场的照射量和角分布的测量结果。该装置在高压450千伏、峰值电流110千安、工作脉冲宽度20—30纳秒时,窗口的照射率为10~(10)伦/秒。文中讨论了 LiF-TLD 的分散性,并给出了对该装置的辐射防护评价。     

XPS and optical studies of Xe-implanted and annealed YSZ single crystals

Xe⁺ ion implantation with 200 keV was completed at room temperature up to a fluence of 1 × 10¹⁷ ion/cm² in yttria-stabilized zirconia (YSZ) single crystals. Optical absorption and X-ray photoelectron spectroscopy (XPS) were used to characterize the changes of optical properties and charge state in the as-implanted and annealed crystals. A broad absorption band centered at 522 or 497 nm was observed in the optical absorption spectra of samples implanted with fluences of 1 × 10¹⁶ ion/cm² and 1 × 10¹⁷ ion/cm², respectively. These two absorption bands both disappeared due to recombination of color centers after annealing at 250 °C. XPS measurements showed two Gaussian components of O_1s spectrum assigned to Zr–O and Y–O, respectively, in YSZ single crystals. After ion implantation, these two peaks merged into a single peak with the increasing etching depth. However, this single peak split into two Gaussian components again after annealing at 250 °C. The concentration of Xe decreased drastically after annealing at 900 °C. And the XPS measurement barely detected the Xe. There was no change in the photoluminescence of YSZ single crystals with a fluence of 1 × 10¹⁷ ion/cm² after annealing up to 900 °C.     

Optical absorption of metallic Zn nanoparticles in Zn ion implanted sapphire

Zn⁺ ion implantation (48 keV) was performed at room temperature up to a fluence of 5 × 10¹⁷ cm⁻² in -Al₂O₃ single crystals. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and optical absorption spectroscopy were utilized to characterize the optical properties, chemical charge states and the microstructure of embedded metallic Zn nanoparticles, respectively. XPS analysis indicated that implanted Zn ions are in the charge state of metallic Zn⁰. TEM analysis revealed the metallic Zn nanoparticles of 3–10 nm in the as-implanted sample at a fluence of 1 × 10¹⁷ cm⁻². A selected area electron diffraction (SAD) pattern indicates the random orientation of the Zn nanoparticles. A clear absorption peak appeared gradually in the optical absorption spectra of the as-implanted crystals, due to surface plasma resonance (SPR) of Zn nanoparticles. The wavelength of the absorption peak shifted from 260 nm to 285 nm with the increasing ion fluence, ascribed to the growth of Zn nanoparticles.     

重水浓度与吸光度关系曲线类型研究

重水作为反应堆的慢化材料,其浓度直接影响反应堆的安全和性能。为研究其重水浓度与吸光度间的关系曲线类型,基于朗伯-比尔定律,从理论上推导出液态重水中某种水分子的红外吸收峰分别与0~2种其他水分子的红外吸收峰发生重叠时重水浓度与吸光度间的关系式,分情况对二者之间的关系曲线类型进行讨论。采用傅里叶变换红外光谱仪,测得浓度为0.015%~99.98%（摩尔比）的重水标准样品吸收光谱,对重水浓度和吸光度间的关系曲线类型进行验证,理论推导与实际吻合。研究表明,一般情况下,宽浓度范围内,重水浓度与吸光度间的关系曲线类型为二次曲线;窄浓度范围内,关系曲线类型为线性。特殊情况下,吸光度为定值或关系曲线类型为线性。     

A Comparison of Linac and 60Co Response of the CD4007UBE CMOS Inverter

The n-channel saturated threshold voltage shift of a complementary metal-oxide semiconductor (CMOS) inverter was measured as a function of average and peak dose rate irradiation derived from an electron linear accelerator (LINAC). At peak dose rates below 108 rad(Si)/s, the results are dose-rate-independent and comparable to those obtained using a steady-state 60Co source; at higher peak dose rates, less damage per unit dose was observed.