多发性硬化症显像剂~(11)C-CIC的合成

自动化合成了靶向髓磷脂(myelin)的PET显像剂4-(4-(4-氨基苯乙烯基)-2,5-二甲氧基苯乙烯基)-[N-甲基-11碳]苯胺(11 C-CIC),通过研究其在小鼠生物体及大鼠大脑中的分布,判断其作为多发性硬化(multiple sclerosis,MS)诊断或疗效评价的可行性。在多功能模块上将11 C-CH3-Triflate直接与前体反应,经HPLC分离、纯化得到11 C-CIC,采用NH小鼠用于研究11 C-CIC的生物学分布,Wistar大鼠行Micro PET/CT显像。11 C-CIC合成效率为55%~65%(n10),放化纯度大于99%,比活度为60GBq/μmol。11 C-CIC的体外稳定性较差,加入10g/L的抗坏血酸能防止其分解。11 C-CIC初始脑摄取为2.78%ID/g,放射性主要通过肝、肾排泄。Micro PET/CT显像表明,大鼠大脑对11 C-CIC摄取较好。结果表明,制备11 C-CIC时需加入抗坏血酸以提高其体外稳定性,11 C-CIC有可能应用于髓鞘斑显像,用于诊断或评价MS的进展。     

5-羟色胺转运蛋白显像剂~(11)C-DASB的自动化合成及Micro PET/CT显像

目的:自动化合成5-羟色胺转运蛋白显像剂11 C-DASB并进行大鼠Micro PET/CT显像;方法:通过改变甲基化试剂、溶解前体溶剂及反应条件,得到优化的标记条件作为碳-11多功能合成模块的输入参数,进行自动化合成11 C-DASB,大鼠静脉注射11 C-DASB 45 min后进行显像;结果:采用11 C-CH3-Triflate作为甲基化试剂,通入新配制的含1mg去甲基DASB前体的500μL DMSO溶液内,80℃下加热2min,标准率为63.7%,大鼠显像表明,11 C-DASB特异性的浓聚于SERT富集区域;结论:经优化,11 C-DASB自动化合成可得到较高产率,大鼠显像表明,其特异性浓聚于SERT富集区域,有望作为5-羟色胺转运蛋白显像剂。     

~(11)C-CH_3-Triflate甲基化法合成~(11)C-PK11195

利用11C-CH3-Triflate作为甲基化试剂,与去甲基前体1-(2-氯苯基)-N-(1-甲基丙基)-异喹啉-3-氨甲酰(nor-PK11195)进行甲基化反应合成N-[11C]甲基-N-(1-甲基丙基)-1-(2-氯苯基)异喹啉-3-氨甲酰(11C-PK11195),并建立了11C-PK11195的自动化合成方法。结果显示,以11C-CH3-Triflate为甲基化试剂合成11C-PK11195,在nor-PK11195用量为0.5~1.0 mg、反应温度90℃、反应时间5 min时,其标记率为51.7%±5.6%,11C-PK11195注射液的化学纯度和放化纯度均98%,比活度0.21 TBq/g。以上结果表明,11C-CH3-Triflate甲基化法可提高11C-PK11195标记率,缩短反应时间,降低前体用量;所制备的11C-PK11195注射液能够满足PET临床要求。     

~(18)F和~(11)C标记的氨基酸类分子探针的合成及应用研究进展

PET/CT显像作为一种诊断肿瘤、评价疗效和预后的有力工具得到了快速的发展。氨基酸类正电子药物被临床证明是可以弥补当前18F-FDG PET/CT不足的重要药物,不像18F-FDG,氨基酸类分子探针在正常脑组织中的摄取很低,在良性的病变如炎症、水肿、坏死和纤维化的组织几乎不摄取,可以提高PET/CT显像的特异性,其合成标记的研发日益得到重视。本文重点介绍了当前利用短半衰期正电子核素18F和11C标记合成正电子类氨基酸的方法学和初步应用研究的最新进展。     

在线合成心肌灌注显像剂:碳-11三苯甲基磷

99mTc-MIBI是常用的心肌灌注显像剂,肝摄取高,临床应用有一定的影响。11C-三苯甲基磷(11C-TPMP)为脂溶性正一价阳离子,用于心肌显像能得到更好的分辨率。以11CH3-Triflate为甲基化试剂,采用LOOP法在线合成了11C-TPMP,研究了11C-TPMP在正常小鼠的分布,正常大鼠行Micro PET显像,并与4位18F-苯基三苯基磷(18F-FTPP)比较。结果显示,LOOP法合成11C-TPMP效率大于90%(校正),放化纯度大于98%。正常小鼠心肌有高的摄取,注射后5 min和60 min,心肌摄取分别为(71.9±19.9)%ID.g–1和(12.87±0.81)%ID.g–1,肝摄取低,注射后5 min和60 min心肝摄取比分别为11.57和3.2。正常大鼠micro PET显像显示,从20 min到60 min,心肌显像清晰,肝未显像。表明LOOP法可高效合成11C-TPMP,11C-TPMP是一个很有希望的心肌灌注显像剂。     

~(64)Cu-DOTA-SPIONs-PEG-FA:靶向叶酸受体阳性肿瘤的PET/MRI双模态显像探针

报道了一种可用于叶酸受体阳性肿瘤显像的PET/MRI双模态显像探针(~(64)Cu-DOTA-SPIONs-PEGFA)的合成、初步的生物学评价及PET/CT和MRI显像结果。该探针由包覆了生物相容性的聚乙二醇(poly ethylene glycol,PEG)、超顺磁氧化铁纳米粒子(superparamegnetic iron oxide nanoparticles,SPIONs)、叶酸(folic acid,FA)、1,4,7,10-四乙酸-1,4,7,10-四氮杂环十二烷(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid,DOTA)和正电子放射性核素~(64)Cu组成。经纯化后,~(64)Cu-DOTA-SPIONs-PEG-FA放化纯大于98%。荷KB裸鼠体内分布显示:~(64)Cu-DOTA-SPIONs-PEG-FA在肝脏、脾脏和肺中的放射性摄取较高,与非靶向标记物~(64)Cu-DOTA-SPIONs-PEG-OH比较,其对KB细胞瘤有明显的靶向作用。在MRI和PET/CT模式下,KB肿瘤能被较清晰地显像。~(64)Cu-DOTA-SPIONs-PEG-FA作为KB细胞肿瘤的PET/MRI双模态显像剂,有待于进一步深入研究以改善其标记率、稳定性和比活度等。     

18F-FLT MicroPET评估顺铂对A549肺癌早期疗效反应的研究

目前实体瘤疗效评价标准存在诸多不足,为了对抗肿瘤药的早期药效进行更精准的评价,给肺癌A549模型鼠以灌胃方式灌注顺铂进行治疗,并于给药前后分别进行¹⁸F-FLT MicroPET显像,根据瘤组织的放射性摄取值变化评价顺铂对肺癌A549模型鼠的早期疗效,同时采用传统抗肿瘤药药效评价方法作对比,结合病理切片进一步验证实验结果。结果显示,给药第2天,MicroPET显像可见治疗组肿瘤的放射性摄取由(4.91±0.71)%ID·g^-1降至(3.87±0.61)%ID·g^-1,降幅达21.28%;而治疗组和空白组的肿瘤体积在给药后9 d才出现显著性差异（P<0.01）。以上结果表明,¹⁸F-FLT MicroPET显像较传统的肿瘤体积测量能更早、更精准地评价顺铂的抗肿瘤药效。     

液相法合成~(11)C-CH_3I的影响因素

本工作对11C-CH3I合成过程中加速器靶内释放11CO2速度、捕获环释放11CO2时间、加热除四氢呋喃(THF)时间、LiAlH4/THF的用量5、7%HI用量及冷却反应管时间等因素对合成效率的影响进行了研究,并对以上参数进行了优化,提高了11C-CH3I的合成效率。经过10批次的条件优化实验,11C-CH3I的合成效率为85%±2.3%,放化纯度大于99%。实验同时表明,LiAlH4/THF和57%HI用量是影响11C-CH3I合成效率的主要因素。     

PET/CT对非小细胞肺癌精确放疗计划的影响

探讨PET/CT对非小细胞肺癌(Non-small Cell Lung Cancer,NSCLC)精确放疗(Precise and Accurate Radiotherapy,PAR)计划的影响。对21例非小细胞肺癌患者行PET/CT检查,分别根据CT和PET/CT进行TNM分期,并将PET/CT图像上的TNM分期和CT分期结果进行比较分析。利用CMS治疗计划系统图像融合软件,组织5名放疗科不同年资医师分别在CT和PET/CT三维图像上独立勾画大体肿瘤体积(Gross Tumor Volume,GTVCT和GTVPET/CT),计算患者GTV的体积值和变异系数,比较放疗科不同医师分别在CT和PET/CT上勾画GTV的差异。结果发现52.38%(11/21例)的患者TNM分期改变,21例患者GTVCT和GTVPET/CT均不相同。PET/CT可改变NSCLC临床分期,进而改变整个治疗计划。PET/CT可明显减小放疗科不同级别医师勾画GTV的差异。     

11C-MET和18F-FDG PET/CT对胶质瘤诊断的价值比较

对26例胶质瘤和18例颅内良性病变患者行18F-FDG和11C-MET PET/CT颅脑显像,定性和半定量分析两种显像图像.结果显示:11C-MET和18SF-FDG PET/CT对胶质瘤诊断的准确率分别为88.6%和65.9%.半定量分析,26例胶质瘤11C-MET摄取值比值TINGmax显著高于18F-FDG的TI...     

Transport properties of U0.7Ce0.3O2 − x

We have determined a number of transport properties of $\text{U}{}_{0.7}\text{Ce}{}_{0.3}\text{O}{}_{\mathrm{2-x}}$ at 1273 K for various deviations from stoichiometry and compared them with available results on $\text{(UPu)O}{}_{\mathrm{2\; ?\; x}}$. They are: the electrical conductivity, Seebeck coefficient, effective charge number and chemical diffusion coefficient.A very characteristic behaviour is observed for the electronic properties of $\text{(UCe)O}{}_{\mathrm{2\; ?\; x}}$. A p-type conduction for all the studied deviations from stoichiometry (up to $\text{x = 3 × 10}{}^{\mathrm{?2}}$) is interpreted in terms of a high electronic disorder in the stoichiometric compound. Electronic disorder at stoichiometry is probably less important in $\text{(UPu)O}{}_{\mathrm{2\; ?\; x}}$, which presents a sharp p-n transition at $\text{x = 5 × 10}{}^{\mathrm{?3}}$.Ionic transport properties obtained on $\text{(UCe)O}{}_{\mathrm{2\; ?\; x}}$ indicate an approximate proportionality between the ionic conductivity resulting from oxygen ions transport and the deviation from stoichiometry. Results available on $\text{(UPu)O}{}_{\mathrm{2\; ?\; x}}$ do not appear to be compatible with ours and some arguments are presented which cast doubt on their validity.     

Equi-chemical-potential curves in ternary uranium oxides MyU1−yO2+x

Using Schuhmann's method the chemical potentials of three components in nonstoichiometric ternary uranium oxides $\text{M}{}_{\mathrm{y}}\text{U}{}_{\mathrm{1?y}}\text{O}{}_{\mathrm{2+x}}$(M = Mg and Pu) have been calculated. The obtained results are shown in the form of equi-chemical-potential curves (surface of partial molar free energy) in the composition triangle. In the hypostoichiometric region the contour lines of the surface are dense and run parallel with each other. Taking account of this fact the difficulty in attainment of homogeneity in the fabrication of mixed oxide fuel is discussed.     

Structural characterization of Nd-doped Hf-zirconolite Ca1−xNdxHfTi2−xAlxO7 ceramics

Because of its high incorporation capacity and of the high thermal neutron capture cross-section of hafnium, Hf-zirconolite (CaHfTi₂O₇) ceramic can be envisaged as a potential waste form for minor actinides (Np, Am, Cm) and plutonium immobilization. In this work, Nd-doped Hf-zirconolite Ca_1−xNd_xHfTi_2−xAl_xO₇ (x = 0; 0.01 and 0.2) ceramics have been prepared by solid state reaction. Neodymium has been used as trivalent actinide surrogate. The ceramic samples structure has been studied by X-ray diffraction and refined by the Rietveld method. This revealed that Nd³⁺ ions only enter the Ca site, whereas part of Hf⁴⁺ ions substitute titanium into Ti(1) sites and Al³⁺ ions mainly occupy the Ti(2) split sites and Ti(3) sites of the zirconolite structure. Using various spectroscopic techniques (electron spin resonance, optical absorption and fluorescence), the environment of Nd³⁺ cations in Hf-zirconolite has been studied and compared with that of Nd³⁺ cations in Zr-zirconolite (CaZrTi₂O₇). Different local environments of Nd³⁺ cations have been detected in Hf-zirconolite that can be attributed to the existence of an important disorder around Nd in the Ca site probably due to the statistical occupancy of the next nearest cationic site of neodymium (a split Ti site) by Ti⁴⁺, Al³⁺ cations and vacancies. No significant differences were observed concerning Nd³⁺ cations environment and distribution in Hf- and Zr-zirconolite ceramics.     

Phase relation and defect structures of nonstoichiometric U4O9±y and UO2+x at high temperatures

Phase relations in the composition range from $\text{UO}{}_{\mathrm{2+x}}$ to $\text{U}{}_3\text{O}{}_{\mathrm{8?z}}$ were studied by electrical-conductivity measurements and X-ray diffraction in the ranges $\text{1025°C ? T ? 1140°C}$ and . The plot of log σ versus log showed straight lines with distinct slopes, which corresponded to four regions ($\text{UO}{}_{\mathrm{2+x}}$, $\text{U}{}_4\text{O}{}_{\mathrm{9?y}}$, $\text{U}{}_4\text{O}{}_{\mathrm{9+y}}$ and $\text{U}{}_3\text{O}{}_{\mathrm{8?z}}$). The existence of the hyperstoichiometric $\text{U}{}_4\text{O}{}_{\mathrm{9+y}}$ phase was suggested in the temperature range from 1025 to 1126°C. The peritectoid temperature ($\text{U}{}_4\text{O}{}_{\mathrm{9\pm y}}\text{= UO}{}_{\mathrm{2+x}}\text{+ U}{}_3\text{O}{}_{\mathrm{8?z}}$) was estimated to be present between 1126 and 1131°C. The partial free enthalpies and entropies for the two-phase equilibrium ($\text{U}{}_4\text{O}{}_{\mathrm{9+y}}\text{+ U}{}_3\text{O}{}_{\mathrm{8?z}}$, and $\text{U}{}_4\text{O}{}_{\mathrm{9?y}}\text{+ UO}{}_{\mathrm{2+x}}$) were calculated and compared with previous results. From the dependence of the electrical conductivity on the oxygen partial pressure the nonstoichiometric defect structures of $\text{UO}{}_{\mathrm{2+x}}$ and $\text{U}{}_4\text{O}{}_{\mathrm{9\pm y}}$ were interpreted as consisting of doubly charged oxygen interstitials (O_i'') and doubly charged oxygen vacancies (V_O''). At room temperature, the homogeneity range of the U₄O₉ phase was investigated with a Debye-Scherrer camera.     

Neutron production cross sections and energies for the reactions 7Li(p,n)7Be and 7Li(p,n)7Be1

Center-of-mass best values for the normalized Legendre coefficients and the 0° differential cross sections as functions of input energy have been derived from various experimental results for the reactions ⁷Li(p,n)⁷Be and ${}^7\text{Li}\text{(p,n)}{}^7\text{Be}{}^1$ (431 keV). This information has been used to calculate laboratory differential cross sections as functions of the laboratory proton energy and neutron emission angle which are given in tabular form together with the corresponding neutron energies.     

Effects of ion irradiation on the mechanical properties of SiNawOxCyHz sol-gel derived thin films

A study of the effects of ion irradiation of hybrid organic/inorganic modified silicate thin films on their mechanical properties is presented. NaOH catalyzed SiNa_wO_xC_yH_z thin films were synthesized by sol-gel processing from tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) precursors and spin-coated onto Si substrates. After drying at 300 °C, the films were irradiated with 125 keV H⁺ or 250 keV N²⁺ at fluences ranging from 1 × 10¹⁴ to 2.5 × 10¹⁶ ions/cm². Nanoindentation was used to characterize the films. Changes in hardness and reduced elastic modulus were examined as a function of ion fluence and irradiating species. The resulting increases in hardness and reduced elastic modulus are compared to similarly processed acid catalyzed silicate thin films.     

Investigations on UAlx-Al dispersion fuels for high-flux reactors

The paper outlines the preparation of $\text{UAl}{}_{\mathrm{x}}\text{-Al}$ dispersion fuel plates for thermal high-flux reactors. The work described includes the preparation of UAl₂, UAl₃ and UAl₄ compounds by induction melting and their processing to Al-clad fuel plates using the picture-frame technique. Induction melting in alumina crucibles and subsequent homogenisation can be used to produce relatively homogeneous $\text{UAl}{}_{\mathrm{x}}$ compounds. After comminution to a predetermined size range and blending with Al, the pressed compacts can be rolled into Al-clad fuel plates. UAl₃ and UAl₂ compounds react with Al forming UAl₄. The reactions begin at about 673 K, and have an activation energy of 52.6 and 42.6 kcal/mol, respectively. The measured properties of the dispersions and UAl-phases such as thermal expansion, thermal and electrical conductivity, tensile strength, microhardness and hot hardness are affected by the concentration of the dispersed phase and can be explained in the light of existing theoretical models. Due to its potential as a high-flux reactor fuel with higher uranium content the preparation and properties of UAl₂-Al dispersions as well as the preliminary data about their stability under irradiation may be of particular interest.     

Damage creation in ion irradiated Si1−xGex/Si structures

Strained SiGe/Si structures have been proposed as substrates for fabrication of high speed metal oxide semiconductor transistors. However, influence of strain and/or presence of Ge atoms on damage creation during ion irradiation have not been explored to a significant extent. In this study, Rutherford backscattering spectrometry (RBS) was used to characterize Si_1−xGe_x/Si structures irradiated by 140 keV He⁺ ions at room temperature. When compared with pure Si, strained samples show enhanced damage accumulation as a function of He fluence. Channeling angular scans did not reveal any specific configuration of displacements. Possible mechanisms for enhanced damage in strained Si are discussed.     

Wavelengths and classifications of emission lines due to 2s22pn−2s2pn + 1 and 2s2pn−2pn + 1 transitions, Z ≤ 28

Tables of wavelengths and classifications of observed emission lines due to 2s²2pⁿ?2s2p^{n + 1} and 2s2pⁿ?2p^{n + 1} transitions are presented. The accuracy of data derived from different experimental methods is discussed. Revised and predicted wavelengths are added. Energy levels are derived from the wavelength data.     

Statistical thermodynamic study of the ternary compounds ThXyHx (X = C,N;y < 1;x < 2)

The stability and the nature of bonding in hypostoichiometric ThH₂, hcp ThC_0.46H_x and fcc ThN_yH_x (y = 0.486 and 0.692) are studied on the basis of statistical thermodynamics. The discussions are made in terms of the atomic partition function of H in these condensed phases and of the interaction energy terms. It is concluded that the nature of bonding in ThN_yH_x is approximately the same as that in ThH₂. On the other hand, the nature of bonding in ThC_yH_x is found to be significantly different from that in ThH₂.