用于校准192Ir医用源的阱型电离室

研制了一种用于校准医用¹⁹²Ir源的阱型电离室。该电离室的灵敏体积约为271cm³，在极化电压约为300V时，电离室的离子收集效率约为99.96%，总位置灵敏度变化小于0.3%。该阱型电离室对¹⁹²Ir的响应因子为0.230nA/GBq，其相对合成不确定度为1.5%，与IAEA校准过的阱型电离室比对，在不确定度范围内一致。     

Effect of B-site Al substitution on hydrogen production of La0.4Sr0.6Mn1-xAlx (x=0.4, 0.5 and 0.6) perovskite oxides

Thermochemical water splitting using perovskite oxides as redox materials is one of the important way to use solar energy to produce green hydrogen. Thus, it is hence important to discover new materials that can be used for this purpose. In this regard, we focused on Al-substituted La_0.4Sr_0.6Mn_1-xAl_xO₃ (x = 0.4, 0.5 and 0.6) perovskite oxides, namely as La_0.4Sr_0.6Mn_0.6Al_0.4 (LSMA4664), La_0.4Sr_0.6Mn_0.5Al_0.5 (LSMA4655), and La_0.4Sr_0.6Mn_0.4Al_0.6 (LSMA4646) which have been successfully synthesized. Herein, synthesized LSMA4664, LSMA4655, and LSMA4646 were subjected to three consecutive thermochemical cycles in order to determine their oxygen capacity, hydrogen capacity, re-oxidation capability and structural stability following three cycles. Thermochemical cycles were carried out at 1400 °C for reduction and 800 °C for the oxidation reaction. LSMA4646 exhibited the highest O₂ production capacity with 275 μmol/g among the other perovskites employed in the study. Moreover, LSMA4646 has also the highest H₂ production, 144 μmol/g, with 90% of re-oxidation capability by the end of three thermochemical water splitting cycles. On the other hand, LSMA4664 has the lowest H₂ production and only kept approximately one-third of its hydrogen production capacity by the end of cycles. Thus, the current study provides insight that the increase in the Al-substitution enhances both oxygen and hydrogen production capacity. Besides, increasing the Al amount increases the structural stability during the redox reactions, the re-oxidation capability was also increased from 38% to 89% after thermochemical cycles.     

~(15)N标记S-苄基-L-半胱氨酸含量及其同位素丰度检测

建立了一种测定发酵液中15N标记S-苄基-L-半胱氨酸(SBC)含量的高效液相色谱法(HPLC),该方法采用Cosmosil C18(5μm,150 mm×4.6 mm)色谱柱为分离柱,2,4-二硝基氟苯为衍生剂,0.05 mol/L乙酸钠缓冲溶液(pH=6.5,含10 mL/L N,N-二甲基甲酰胺)与V(乙腈)∶V(水)=3∶1为流动相,梯度洗脱,流速1.0 mL/min,检测波长为350 nm,柱温为30℃;并采用微量高温燃烧-质谱法对15N标记SBC样品的同位素丰度进行了检测。结果显示,SBC浓度为0.2~1.0 g/L时,与其峰面积呈良好的线性关系,y=3×106x-4.16×104,R2=0.998 6,平均加标回收率97.30%,检测限为3.95×10-4g/L,测定结果的相对标准偏差为0.55%;15N标记SBC丰度检测时,最小称样量为2 mg,最佳反应温度为530℃,反应时间为3 h;15N丰度测定值的相对标准偏差为0.17%。     

中国137Cs本底值区域分布研究

137Cs区域本底值的确定是应用137Cs法研究土壤侵蚀的首要问题.本文利用Walling和He的137Cs本底值计算模型和软件对中国137Cs本底值区域分布进行了模拟计算.结合前人对中国不同区域137Cs本底值的研究结果,将各区域137Cs实测本底值同模拟值进行比较,指出了模拟结果存在的主要问题,在此基础上讨论了中国137Cs本底值的区域分布特点和影响中国137Cs区域本底值的主要因素.     

无侵蚀非农耕地土壤137Cs深度分布入渗过程模型

在阐明土壤中137Cs扩散与迁移过程的基础上,建立了无侵蚀非农耕地土壤137Cs深度分布入渗过程模型,再现了重庆开县和陕北子长两个剖面137Cs深度分布的变化过程.重庆开县剖面137Cs深度分布(2004年)为指数衰减形态,表层土壤137Cs浓度最高,137Cs深度分布形态系数ho=0.0997 cm-1,入渗系数D=0.8006cm2·a-1.陕北子长剖面137Cs深度分布(2001年)为非指数衰减形态,次表层土壤浓度最高,全剖面拟合的深度分布形态系数ho=0.0825 cm-1,入渗系数D=1.24 cm2·a-1.子长剖面137Cs深度分布为非指数衰减形态的原因主要是表层和次表层土壤随深度增加土壤孔隙度或水分入渗速率急剧降低,导致137Cs入渗速率随深度增加而降低,137Cs入渗系数(D)为负值.     

苯甲酰胺类多巴胺D2受体显像剂18F-FSABZM的合成和标记

将5-硝基取代苯甲酰胺类化合物经硝基还原、N-双羟乙基化、甲磺酰化等反应制备氟标记前体,用K222催化进行氟标记,合成了(S)-N-[(1-乙基-2-比咯烷基)甲基]-5-[N-(2-[18F]氟乙基)-N-甲基磺酰基]胺基-2-甲氧基苯甲酰胺(S)-N-[(1-ethyl-2-pyrrolidinyl)methyl]-5-[N-(2-[18F]fluoroethyl)-N-methylsulfonyl]amino-2-methoxy-benzamide,18F-FSABZM).标记前体、冷标记产物和各步合成中间体均经过核磁共振和质谱确证.结果显示,经HPLC检测,标记率为12%-15%,合成及纯化时间80-90 min,纯化后放化纯度大于97%,稳定性好.     

FNS-100正比计数器用于测量快中子场能谱时的干扰分析

为了了解FNS-100正比计数器用于测量快中子场能谱时干扰信号的特性,本文计算分析了60Co产生的低能γ射线以及7 MeV和10 MeV的高能γ射线所产生的干扰,同时模拟了反冲3He核、反冲质子在该正比计数器中产生的干扰影响.计算结果表明,γ射线对快中子能谱测量几乎没有影响,而反冲3He核和反冲质子存在比较大的影响.     

两种油溶性离子液体与进口添加剂的摩擦学性能对比

目的 对比研究合成的油溶性离子液体(IL)N/P、P/P与传统极压抗磨添加剂IR 349、IR 353和FM 3606对85W/90 GL–5齿轮油摩擦学性能的影响。方法 以IL和传统极压抗磨剂为添加剂,加剂量为1%,在85W/90基础上制备5种润滑剂,空白样85W/90作为对照,通过同步热分析仪测试其热分解温度,采用点面往复摩擦形式在SRV–Ⅳ摩擦机上对其减摩抗磨性能进行研究,采用四球摩擦机测试其极压承载能力。通过环境扫描电子显微镜(ESEM)、三维轮廓扫描仪、X射线光电子能谱仪(XPS)对各润滑剂润滑后对应的磨斑进行微观形貌表征并对其元素组成进行分析。结果 IL的加入在很大程度上提高了85W/90的热分解温度。在50 ℃条件下,含有IL添加剂的齿轮油表现出更为优异的减摩抗磨性能,在150 ℃条件下,含IL添加剂的齿轮油与含传统极压抗磨剂的齿轮油抗磨性能相当,而前者减摩性能更为优异。极压承载能力测试表明,所合成的IL在一定程度上改善了85W/90的油膜强度。根据XPS分析结果推测,IL添加剂在外界应力(热应力、机械应力)下分解后,与金属表面反应并生成具有良好润滑效果的边界薄膜。结论 2种油溶性IL可明显改善齿轮油的摩擦学性能,可部分替代一系列进口添加剂,为后续进一步发展绿色、高性能润滑添加剂提供了一定思路,但IL的润滑机制仍值得深入探讨。     

固体超强酸La3+-SO42-/TiO2-Fe2O3催化合成对羟基苯甲酸丁酯

以固体超强酸La3+-SO42-/TiO2-Fe2O3为催化剂合成了对羟基苯甲酸丁酯,考察了原料配比、催化剂用量、反应温度和反应时间等因素对产品收率的影响。试验结果表明:La3+-SO42-/TiO2-Fe2O3是合成对羟基苯甲酸丁酯的良好催化剂,当n(丁醇)/n(对羟基苯甲酸)=4.0,催化剂用量为对羟基苯甲酸质量的6%,反应温度120℃,反应时间4.0 h,对羟基苯甲酸丁酯的收率达到89.27%。     

The use of computational fluid dynamics to study furnace effects in ITS-90 fixed points realizations

Together with the impurities, the thermal fluxes are one of the major sources of uncertainty during the realization of the International Temperature Scale of 1990 (ITS-90) defining fixed points. The use of computational fluid dynamics (CFD) is a valuable tool to develop models that describe the time evolution of the phase transformation (essentially the evolution of the solid–liquid interface) as a function of given theoretical assumptions and given parameters (furnace thermal gradients, freezing initiation, ambient temperature and insulation). The models can be validated by observing the impact of the selected parameters on the observed corresponding melting curves and used to achieve a full understanding of these thermal effects and their impact on uncertainty. This paper proposes an ITS-90 metallic fixed points CFD model together with some results about the influence of the furnace thermal gradients and the freezing initiation techniques.