掺Pb超导体（Bi2—xPbx）Ca2.5Nd0.5Cu2O8＋y的正电子寿命研究

室温测量了（Ｂｉ２－ｘＰｂｘ）Ｃａ２．５Ｎｄ０．５Ｃｕ２Ｏ８＋ｙ超导体的正电子寿命与Ｐｂ含量的关系。在２２１２相发现随着Ｐｄ含量的增加正电子体寿命相应地减小，分析表明，这是由于Ｐｂ替换了Ｂｉ，使电子从Ｃｕ－Ｏ面或其它晶位迁移到Ｂｉ－Ｏ层，并导致Ｂｉ－Ｏ层电子密度增加所致。     

MOSSBAUER SPECTROSCOPY OF HIGH T_c YBa_2 (Cu_(3-x)Fe_x )O_y

ＭＯＳＳＢＡＵＥＲＳＰＥＣＴＲＯＳＣＯＰＹＯＦＨＩＧＨＴ＿ｃＹＢａ＿２（Ｃｕ＿（３－ｘ）Ｆｅ＿ｘ）Ｏ＿ｙ￥ＬｉＳｈｉ（李士）ａｎｄＬｉＹｉｎｈｕａ（李印华）（ＩｎｓｔｉｔｕｔｅｏｆＨｉｇｈＥｎｅｒｇｙＰｈｙｓｉｃｓ，Ｂｅｉｊｉｎｇ１０００８０，Ｃｈｉ...     

粉末Ba_(0.95)M_(0.05)FBr:Eu~(2+)(M=Sr,Ca)的光激励发光研究

ＢａＦＢｒ：Ｅｕ２＋、Ｂａ０.９５Ｓｒ０.０５ＦＢｒ：Ｅｕ２＋以及Ｂａ０.９５Ｃａ０.０５ＦＢｒ：Ｅｕ２＋粉末样品在未经Ｘ射线或紫外光辐照之前,用长波长（＞４００ｎｍ）光激励样品,都可观测到对应于Ｅｕ２＋４ｆ６５ｄ→４ｆ７跃迁的３９０ｎｍ发光,该发光与样品制备过程中形成的Ｆ心有关。在样品的激励光谱中可以观测到两组峰,中心峰值位于５３５ｎｍ的峰相应于Ｆ（Ｆ－）心电子的激励,而峰值位于７０８ｎｍ的峰可能源于Ｆ（Ｂｒ－）心或Ｆ（Ｂｒ－）心聚合体电子的激励。当少量（５％）半径较小的碱土金属离子Ｃａ２＋（半径为０. ０９９ｎｍ）或Ｓｒ２＋（半径为０．１１３ｎｍ）替代Ｂａ２＋（半径为０．１３５ｎｍ）进入晶格时,随着离子半径的减小,位于５３５ｎｍ和７０８ｎｍ的激励峰强度随之减小,而且分别在５８０ｎｍ和６５０ｎｍ或５７５ｎｍ和６４５ｎｍ处出现肩峰,在波长为５０－４００ｎｍ的吸收光谱中发现,由于小半径碱土金属离子的替代,７９ｎｍ和８３ｎｍ吸收峰红移,且出现新的吸收峰。证实了 Ｓｒ２＋或 Ｃａ２＋部分替代 Ｂａ２＋而产生新的色心： Ｆ（ Ｆ－,Ｓｒ２＋）、Ｆ（Ｂｒ－,Ｓｒ２＋）心或Ｆ （Ｆ－,Ｃａ２＋）、Ｆ（Ｂｒ－,Ｃａ２＋）心,也对应于     

非晶合金Fe_（73．1）Cu_（1．2）Nb_（3．2）Si_（12．5）B_

采用Ｍ　ｓｓｂａｕｅｒ效应和ＸＲＤ分析方法研究了非晶合金Ｆｅ７３．１Ｃｕ３．２Ｎｂ３．２Ｓｉ１２．５Ｂ１０．０的晶化。实验表明，该非晶合金有两个晶化阶段。在第一阶段晶化后，样品主要由ＤＯ３型的ａ—ＦｅＳｉ合金的超细颗粒和作为晶界的非晶相两部分组成。随着退火温度的上升，晶化相的含量增加，非晶相含量减少、在第二阶段晶化后，残余的非晶相就晶化为Ｆｅ２Ｂ和Ｆｅ２３Ｂ６化合物以及可能为Ｆｅ－Ｎｂ－Ｂ之类的顺磁相。     

YBa2Cu3—xSnxOy超导体系的正电子寿命谱研究

研究了Ｓｎ作Ｃｕ位元素替代的ＹＢａ２Ｃｕ３－ｘＳｎｘＯｙ超导体系（ｘ＝０－１．５）的正电子寿命谱，计算了局域电子密度和缺陷浓度的变化，发现了存在于高浓度替代区域（ｘ＝０．８－１．０）的正电子湮没特征，讨论了对超导电性的影响以及相应的物理机制。     

YBa_2Cu_（3－x）Sn_xO_y超导体系的正电子寿命谱研究

研究了Ｓｎ作Ｃｕ位元素替代的ＹＢａ２Ｃｕ３－ｘＳｎｘＯｙ超导体系（ｘ＝０－１．５）的正电子寿命谱，计算了局域电子密度和缺陷浓度的变化；发现了存在于高浓度替代区域（ｘ＝０．８－１．０）的正电子湮没特征；讨论了对超导电性的影响以及相应的物理机制。     

非晶合金Fe73.1Cu1.2Nb3.2Si12.5B10.0晶化的Mossbauer研究

采用Ｍｏｓｓｂａｕｅｒ效应和ＸＲＤ分析方法研究了非晶合金Ｆｅ７３．１Ｃｕ１．２Ｎｂ３．２Ｓｉ１２．５Ｂ１０．０的晶化。实验表明，该非晶合金有两个晶化阶段。在第一阶段晶化后，样品主要由ＤＯ３型的α－ＦｅＳｉ合金的超细颗粒和作为晶界的非晶相两部分组成。随着退火温度的上升，晶化相的含量增加，非晶相含量减少。在第二阶段晶化后，残余的非晶相就晶化为Ｆｅ２Ｂ和Ｆｅ２３Ｂ６化合物以及可能为Ｆｅ－Ｎｂ－Ｂ之类的顺     

MOSSBAUER STUDY ON REDUCIBILITY OF SUPPORTED Eu_2O_3

ＭＯＳＳＢＡＵＥＲＳＴＵＤＹＯＮＲＥＤＵＣＩＢＩＬＩＴＹＯＦＳＵＰＰＯＲＴＥＤＥｕ_２Ｏ_３ＷｕＸｉａｏｈｕａ，ＨｓｉａＹｕａｎｆｕ，Ｈ．Ｍ．Ｗｉｄａｔａｌｌａｈ~１（ＤｅｐａｒｔｍｅｎｔｏｆＰｈｙｓｉｃｓ，ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｎａｎｊ?..     

正电子湮没寿命与BaF_xCl_（2－x）：Eu~（2＋）中缺陷的关系

讨论了光激励发光材料ＢａＦｘＣｌ２－ｘ：Ｅｕ２＋中的缺陷与正电子湮没寿命的关系．通过实验结出随着ｘ值的改变即Ｆ／Ｃｌ比值的变化对形成Ｆ色心的影响，并且给出了ｘ值与Ｆ色心的种类与浓度的关系．     

PMCBP与中性萃取剂对铕的协同萃取

研究了１－苯基－３－甲基－４（２－氯苯氯基）哟唑酮－５（ＰＭＣＢＰ）与三辛基氧化膦（ＴＯＰＯ）、二正辛基亚砜（ＤＯＳＯ、二环己基亚砜（ＤＣｙＨＳＯ）和磷酸酸古丁酯（ＴＢＰ）的二甲苯溶液从盐酸介质中对肴的协同萃取，实验证实有明显的协萃效应，采用斜率法测定了ＰＭＣＢＰ单独和协萃铕的配合物组成，它们分别为ＥｕＡ２．Ｃｌ．ＨＡ和ＥｕＡ２．Ｃｌ．Ｂ（Ｂ为ＴＯＰＯ、ＤＯＳＯ、ＤＣｙＨＳＯ ＴＢＰ）。计算了它们     

Synthesis of 2-[~(18)F]fluoro-3-[2(S)-2-azetidinylmethoxy]pyridine as a radioligand for imaging nicotinic acetylcholine receptors

Nicotinic acetylcholine receptors (nChRs) are involved in the various pharmacological effects or disease states. In order to study the central nChRs by PET or SPECT, some radioligands have been investigated. In this paper, the procedure for synthesis of 2-[18F]fluoro-3-[2(S)-2-azetidinylmethoxy]pyridine (2-[18F]-A-85380), a potential PET ligand for in vivo imaging nicotinic acetylcholine receptor was described. 2-[18F]-A-85380 was prepared from the precursor, 2-nitro-3-[(1-(tert-butoxycarbonyl)-2-(S)-azetidinyl)methoxy]pyridine(4), which was synthesized with commercial (S)-2-azetid- inecarboxylic acid as starting material. The whole procedure for radiosynthesis and purification was executed in about 1h and 45-55% of the added fluorine-18 was found in the purified 2-[18F]-A-85380, with specific activity of 1.0-2.2×1011 Bq/μmol.     

Effect of Low-frequency Power on F, CF2 Relative Density and F/CF2 Ratio in Fluorocarbon Dual-Frequency Plasmas

Effect of low-frequency power on F, CF₂ relative density and F/CF₂ ratio, in C₂F₆, C₄F₈ and CHF₃ dual-frequency capacitively couple discharge driven by the power of 13.56 MHz/2 MHz, was investigated by using optical emission spectroscopy. High F, CF₂ relative density and high F/CF₂ ratio were obtained in a CHF₃ plasma. But for C2F6 and C4F8 plasmas, the F, CF₂ relative density and F/CF₂ ratio all decreased significantly due to the difference in both reactive paths and reactive energy. The increase of LF power caused simultaneous increase of F and CF₂ radical relative densities in C₄F₈ and CHF₃ plasmas, but led to increase of F with the decrease in CF₂ relative densities in C₂F₆ plasma due to the increase of lower energy electrons and the decrease of higher energy electrons in EEDF.     

STUDY ON THE ACCUMULATION OF ENRICHED URANIUM UO_2F_2 IN SUBCELLULAR LEVEL BY ELECTRON MICROSCOPIC AUTORADIOGRAPHY

In this paper we try to study the retentive peculiarity of soluble enriched uranium UO2F2 in subcellular level by electron microscopic autoradiography. The early dynamic accumulation of radioactivity in the body showed that enriched uranium UO2F2 was chiefly localized in kidney, especially accumulated in epicyte of kidney near- convoluted tubule. In liver cells, enriched uranium UO2F2 at first deposited in the nucleus and the cytoplasm, then accumulated in mitochondria selectively and lysosome as well. The electron microscopic autoradiographic study showed that the dynamic retention of radioactivity of enriched uranium UO2F2 in skeleton rose steadily throughout the exposure. Enriched uranium UO2F2 chiefly deposited in nucleus and mitochondria of the osteoblast as well as osteoclast.     

UF4在氧或湿氧中热化学反应研究

采用显微激光拉曼光谱技术、称重及形貌观察等手段,开展了UF₄在氧气或相对湿度93%湿氧气氛中的热化学反应实验研究,获取了UF₄不同温度时效后的质量、颜色及失重情况,以及反应前后不同铀化合物的拉曼光谱。结果表明：UF₄在氧气或湿氧中加热至200 ℃时,性质稳定,其拉曼光谱基本无变化;250~600 ℃时,样品表面颜色发生明显变化。拉曼光谱分析发现,在氧气气氛中有UO₂F₂、UO₂、U₃O₈,在湿氧气氛中有UO₂F₂、UO₂F₂•2H₂O、UO₂F₂•nH₂O、UO₂、U₃O₈等多种铀化合物生成。随着温度的升高,UF₄在氧气中的化学反应速率呈现由慢到快再到慢的变化趋势。     

Investigation of Electron Capture Cross Section Additivity for CF4 C2F6 and C4F8 at Ep = 0.8 and 1.5 MeV

We have investigated single electron capture cross section additivity for the fluorocarbon molecules, CF4, C2F6 and C4F8 at proton energies of 0.8 and 1.5 MeV. Applying the post-collision-interaction (PCI) model to the case where the electron capture cross sections,?10, for C and F are quite similar, we are able to provide an internally consistent parameterization of these molecular electron capture cross sections at each proton energy, ?10 (CmFn), in terms of "atomic" ?10 values for C and F, using the relationships ?10 (CmFm) = TmnC m?10 (C) + TmnF n?10 (F) or ?10 (CmFn) = ?mnCF [m?10(C) + n?10(F)] The Tmn terms are transmission fractions directly calculable from the PCI model; ?mnCF is the weighted transmission fraction which characterizes each molecule     

Experimental values of transition probabilities for 2s22p3-2s2p4 transitions along the N I like sequence

Transition probabilities for the 2s²2p³²D/²P-2s2p⁴²P and 2s²2p³²D/²P-2s2p⁴²D transitions in O II, F III, Ne IV and Si VIII ions have been determined. The results are compared with atomic structure calculations. A good overall agreement with data based on the NCMET method is observed which underlines the importance of electron correlations for the investigated decay processes     

微波加热法合成O-(2-[18 F]氟乙基)-L-酪氨酸

O-（2-[^18F]氟乙基）-L-酪氨酸（O-（2-[^18F]fluoroethyl）-L-Tyrosine,^18F-FET）是最近研究的氨基酸类脑肿瘤PET显像剂。为了缩短合成时间,简化操作步骤,减少工作人员的辐射剂量,从反应组分、加热方法和反应模式等3个方面改进并优化^18F-FET的“两步法”放射化学合成路线。实验选择L-酪氨酸和氢氧化钠溶液与DMSO作为反应组分,加热方式更换为微波法,采用简化的“一锅式”反应方式,总合成时间缩短至20min,标记率大于95％。     

Remote-controlled module-assisted synthesis of O-（2-[18^F]fluoroethyl）-L-tyrosine as tumor PET tracer using two different radiochemical routes

The positron-emitter fluorine-18 labeled amino acid O-（2-[18^F]fluoroethyl）-L-tyrosine （[18^F]FET） has shown very promising perspectives for brain tumor diagnosis with positron emission tomography （PET）. There have been two existing preparation routes of [18^F]FET named direct nucleophilic radiofluofination of protected L-tyrosine and radiofluoroalkylation of unprotected L-tyrosine, respectively. A general module was designed specifically for the routine synthesis of [18^F]FET, which could be suitable for the present two chemical methods with simple modifications. The fluorinated intermediates and the final product were separated and purified using solid phase extraction （SPE） on the Sep-Pak silica plus cartridge instead of the time-consuming high performance liquid chromatography （HPLC） procedures. The total synthesis time was about 50-60 min with good radiochemical yield （about 20-40%, no-decay-corrected） and good radiochemical purity （more than 97%） for both the synthetic methods.     

Comparative and optimized studies on radiosynthesis of O-（2-[^18F]fluoroethyl）-L-tyrosine

O-（2-[^18F]fluoroethyl）_L-tyrosine （[^18F]FET）, one of radiolabelled amino acids, is a very promising brain tumor positron emission tomography （PET） imaging agent and holds clinical potential. This paper described out a comparative and optimized radiosynthesis of [^18F]FET, concerning three aspects of its two-step preparation method, including reaction components, heating methods and reaction models. As a result, good radiochemical yield （about 45%, no-decay-corrected） and radiochemical purity （more than 95%） were achieved, and total synthesis time of [^18F]FET was shortened within 20 min and radiation exposure time also decreased.     

NaF晶体中电子辐照诱导的F_2~+心和(F_2~+)心产生和衰减的动力学过程

采用电子束在不同温度辐照了纯NaF、NaF:Mg~(++)和NaF:Mn~(++)的样品,测量了这些样品的吸收光谱随温度和时间的变化。降低辐照温度有利于(F_2~+)~*心的生成。F_2~+心的衰减和(F_2~+)~*心的产生包括四个反应:F_2~+心的去电离、F_2~+心的热离解、F_2~+心转化为(F_2~+)~*心和(F_2~+)~*心的直接合成。对于不同的掺杂浓度和辐照条件,不同的反应将起主要作用。(F_2~+)~*心应由F_2~+心、某种辐照损伤和外围的二阶金属离子构成。