β-肾上腺素受体放射配基分析法的条件探讨

本文对β-肾上腺素受体放射配基分析法中的缓冲液、膜受体制备条件、胰蛋白用量、结合与游离配基的分离方法及非特异性结合的控制等方面作了探讨和改进,使方法的稳定性和可靠性有了明显的提高,并对所建方法进行了较完整的考核。     

液闪测量中数据处理的几个问题

本文讨论了放射免疫分析法和免疫放射分析法及受体结合分析法的在线和离线数据处理问题。文章认为,放射免疫分析法的数据处理发展较快,其中四参数和五参数Logitic法及四参数单位点质量作用模型较为理想。模型中较合理地考虑了非特异性结合,且适合于不对称的免疫放射分析法的曲线。用放射配基测定受体的技术及其数据处理的方法发展很快,业已证明用目前最常用的Scatchard法处理数据并不理想。尤其当放射配基与受体的亲和力很高时,Clark模型的应用受到很大的限制,而用最小二乘法拟合Clark模型的改进型能得到满意的结果。     

锶在土壤中的吸附动力学

用动态法测定了锶在核废物处置预选场址土壤中的平衡吸附容量，研究了水相pH值、流速、土壤粒度和锶溶液的初始质量浓度对土壤吸附锶的影响。水相pH值、流速、溶液的初始质量浓度越大，土壤平衡吸附容量越大；土壤粒度越小，土壤平衡吸附容量越大。用常用的吸附动力学方程对实验数据进行了拟合，并对吸附机理进行了探讨。实验结果表明，该放射性废物处置预选场址土壤对锶的最大吸附率为48.8％，吸附性能较差。     

开环式氡析出率连续测量中抽气流率的影响

应用MATLAB对开环式氡析出率测量过程中不同抽气流率下集氡罩内氡浓度随时间的变化规律进行模拟计算,并用实验对计算结果进行了验证。结果表明,在氡析出率测量时保持集氡罩参数不变的情况下,随着抽气流率的增大,集氡罩内平衡氡浓度值减小,达到平衡氡浓度的时间也缩短。实验表明,集氡罩内的平衡氡浓度的减小可最大限度地减小泄露与反扩散的影响;抽气流率的变大使集氡罩内达到平衡氡浓度时间缩短以及集氡罩内的充气均匀性愈好。通过本次实验,获得的抽气流率为1.94-3.0 L·min~(-1),集氡罩底面积为299 cm~2,体积为1.79×10~(-3)m~3。     

~(125)I-心得静的标记及β-肾上腺素能受体的结合试验

本文报道了用生物作用最强的β-受体阻断剂(一)心得静作配基,用~(125)I标记制备高亲和力和高比活性的放射配基。     

M受体亚型放射配基结合－免疫沉淀分析方法的建立及考核

利用１％洋地黄皂甙溶解大鼠脑匀浆Ｍ受体，用非选择性配基３Ｈ－ＱＮＢ标记可溶性Ｍ受体，以自制的Ｍ１、Ｍ２亚型抗血清和固相二抗分别特异性地免疫沉淀相应的亚型，分析单一受体亚型。对方法进行了考核，包括受体的溶解效率、抗原抗体反应时间、抗血清稀释度、反应温度等对分析结果的影响。对大鼠脑Ｍ受体的试验表明，用两种亚型抗血清进行的免疫沉淀分析呈典型的单位点饱和曲线，抗体对配基与受体的结合反应无影响。     

不同初始温度下氩等离子体演化过程研究

本文对不同初始温度下氩等离子体中主要粒子随时间的演化规律进行数值模拟,跟踪各主要成分粒子的浓度随时间的变化,得到放电后氩等离子体中主要带电粒子和中性粒子浓度随时间的变化规律。计算结果表明,氩等离子体化学反应达到平衡所需时间随初始温度升高逐渐减少,活性粒子Ar⁺浓度随时间不断增大,Ar^*、Ar^**浓度随时间先增大后减小,最终趋于稳定值达到平衡状态。     

应用99mTc-NGA进行肝ASGP受体 显像的实验研究

新半乳糖人血清白蛋白(NGA)是肝细胞表面去唾液酸糖蛋白受体(ASGPR)的特异性配基。根据受体与配基结合的原理,报道了以     

介质阻挡放电低温等离子体降解甲基红模拟染料废水的研究

利用介质阻挡放电低温等离子体技术对甲基红模拟染料废水进行降解研究，降解反应在同心管式反应器中进行。考察了放电功率、溶液初始浓度、初始pH、处理时间、气氛条件等单因素的改变对甲基红降解效果的影响，通过测定甲基红521 nm处的吸光度值、溶液pH及颜色变化，分析了甲基红降解历程，并推测了降解机理。研究结果表明：在本实验中，溶液在115 W低放电功率下的处理效果更好，由于处理效果受温度、湿度等影响，放电功率与处理效果间并不呈正相关关系；溶液的初始浓度越高，达到同样的降解效果所需的时间越长；相同条件下，模拟废水的初始pH越低，其处理后的降解效果越好，即酸性条件下更有利于甲基红断键降解。     

生长抑素-葡聚糖的99Tcm标记及体外结合分析

采用还原氨化方法，将天然生长抑素（SMS）与葡聚糖(Dx20)偶联，并以125I－奥曲肽（125I-Tyr3-Octreotide)为放射配基，进行受体竞争结合实验，测定了SMS-Dx50的IC50；以SnCl2为还原剂对SMS-Dx50进行99Tcm标记，并进行99Tcm- SMS-Dx50受体结合分析，考察其对生长抑素受体的亲合能力。结果表明：SMS-Dx50保持了对SMS 2型受体的高亲和力；其IC50与奥曲肽的IC50（0.79 nmol/L）相近,为5.95 nmol/L；99Tcm- SMS-Dx50标记率>85％, 经PD-10柱分离纯化，其放化纯度>98%；99Tcm- SMS-Dx50对生长抑素2型受体特异性结合为25%～40％，保持了较高的亲和力；SMS-Dx50适合于99Tcm标记，可用于生长抑素受体阳性肿瘤诊断的进一步研究     

Influence of void fraction change on plutonium and minor actinides recycling in BWR with equilibrium burnup

A study on the influence of void fraction change on plutonium and minor actinides recycling in standard boiling water reactor (BWR) with equilibrium burnup model has been conducted. We considered the equilibrium burnup model since it is a simple time independent burnup method that can handle all possible produced nuclides in any nuclear system.

The uranium enrichment for the criticality of the reactor diminishes significantly for the plutonium and minor actinides recycling case compared to that of the once-through cycle of BWR case. This parameter decreases much lower with the increasing of the void fraction. A similar propensity was also shown in the required natural uranium per annum. The annual required natural uranium was calculated by assuming that the uranium concentration in the tail of the enrichment plant is 0.25 w%. The amount of loaded fuel reduces slightly with the increment of the void fraction for plutonium and minor recycling in BWR.     

Multi-recycling in the ENHS and the equilibrium core

This work investigates the effect of initial fuel composition, power density and number of recycles on the pitch-to-diameter (P/D) ratio and TRans-Uranium isotopes (TRU) loading required for attaining one of the most important design goals of the Encapsulated Nuclear Heat Source (ENHS) – nearly zero burnup reactivity swing over the 20 years of core life. It is found that the required P/D ratio is sensitive to, primarily, the initial concentration of the short-lived isotope ²⁴¹Pu in the fuel loaded into the first core and to the core power density. The longer is the cooling time of the TRU from LWR spent fuel the smaller becomes the relative ²⁴¹Pu concentration and the smaller becomes the fraction of ²⁴¹Pu lost via radioactive decay and, hence, the smaller needs be the conversion ratio required for nearly zero burnup reactivity swing and the larger can be the P/D ratio. Likewise, the higher is the ENHS power density, the smaller becomes the fraction of ²⁴¹Pu lost via radioactive decay and the larger becomes the P/D required for the first core. The optimal P/D ratio tends to increase with the number of times the fuel is recycled from one ENHS core to the next one. The optimal P/D ratio for the equilibrium composition core is in between 1.53 and 1.59. For a given discharge burnup it tends to somewhat increase with the equilibrium core power density. However, if structural materials will be developed to enable a 20 years core life at elevated power densities, the higher the power density the smaller is the required equilibrium P/D ratio.     

4A沸石对Sr2+的吸附性能的研究

采用间歇法研究在不同环境条件下（浓度、pH值、介质、温度），4A沸石（简称四）对Sr^2＋的吸附性能影响。结果表明：ZF对Sr^2＋的吸附性能比较好，当Sr^2＋浓度为0．05mol/L时，ZF对Sr^2＋的吸附平衡时间约在14天左右，平衡吸附量为526mg／g。Sr^2＋的浓度对ZF的吸附性能影响比较大，其次是溶液的pH值、介质和溶液的温度。ZF对Sr^2＋的平衡吸附量随Sr^2＋浓度的升高而增大，但平衡吸附率和平衡吸附比随着浓度的增大而降低。pH值增大时ZF对Sr^2＋的吸附性能加强。介质溶液含种类、浓度不同的离子时，相对于去离子水介质，ZF对Sr^2＋吸附性能有程度不同的下降；但腐殖酸的存在可以削弱这种影响。温度升高时，ZF对Sr^2＋吸附性能降低。     

Delayed hydride cracking in Zr-2.5Nb tube with the cooling rate and the notch tip shape

The objective of this study is to demonstrate the feasibility of the Kim’s delayed hydride cracking (DHC) model. To this end, this study has investigated the velocity and incubation time of delayed hydride cracking (DHC) for the water-quenched and furnace-cooled Zr-2.5Nb tubes with a different radius of notch tip. DHC tests were carried out at constant K_I of 20 MPa √m on cantilever beam (CB) specimens subjected to furnace cooling or water quenching after electrolytic charging with hydrogen. An acoustic emission sensor was used to detect the incubation time taken before the start of DHC. The shape of the notch tip changed from fatigue cracks to smooth cracks with its tip radius ranging from 0.1 to 0.15 mm. The DHC incubation time increased remarkably with the increased radius of the notch tip, which appeared more strikingly on the furnace-cooled CB specimens than on the water-quenched ones. However, both furnace-cooled and water-quenched CB specimens indicated little change in DHC velocity with the radius of the notch tip unless their notch tip exceeded 0.125 mm. These results demonstrate that the nucleation rate of hydrides at the notch tip determines the incubation time and the DHC velocity becomes constant after the concentration of hydrogen at the notch tip reaches terminal solid solubility for dissolution (TSSD), which agrees well with the Kim’s DHC model. A difference in the incubation time and the DHC velocity between the furnace-cooled and water-quenched specimens is attributed to the nucleation rate of reoriented hydrides at the notch tip and the resulting concentration gradient of hydrogen between the notch tip and the bulk region.     

Possibility of rapidly reporting 226Ra activity in 226Ra-222Rn samples with unknown equilibrium factor by γ spectrometer

This paper reports the observed changes for equilibrium factors between 226Ra and 222Rn with sealing time of the samples. The samples include soil, raw coal, mineral water, cement, rock, etc. Especially the conceptions of "pre-equilibrium time" and "pre-equilibrium factor" have been put forward and methods of measuring and processing data have been given which can be used for rapidly reporting activity of 226Ra in samples with unknown equilibrium factor. It is definitely concluded that, using methods given in the paper, a test report will be completed in 3～7days, instead of one month, after receiving the sample whose activity is not lower than LLD of the spectrometer.     

Evaluation of multiple, self-recycling of reprocessed uranium in LWR

The multiple recycling of uranium in light-water reactors is evaluated to understand its sustainability in multiple recycling scenarios and to evaluate its impact on fuel design and the fuel cycle. Two recycling scenarios were evaluated. One involves the mixing of repU with natU prior to reenrichment. A second involves the mixing of repU with 19.9% EU to provide the new reactor fuel. The equilibrium concentrations of troublesome isotopes such as U-232 and U-236 are evaluated along with the required overenrichment of U-235. It was confirmed that a U-235 overenrichment factor of 0.28 applied to the U-236 concentration is sufficient to meet the cycle reactivity requirements and yields equilibrium enrichments of 5.06% and 5.52% for the two cycles, respectively. The impact on plutonium production and cycle reactivity is further evaluated to ensure the new fuel can meet the desired burnup requirements. Here, the plutonium production was found to be greater and the reactivity swing less in recycling scenarios with higher U-236 concentration.     

Growth of aerosol particles in a steam environment and its effect on removal

In the present work, growth of cesium iodide aerosols in a mixture of steam and air (non-condensable) is investigated. The condensation rates are calculated including the Kelvin and solute effects. Particle growth to its equilibrium size, with and without energy conservation, is calculated for a range of particle size, temperature and surrounding relative humidity. The time required for the particles to grow to their equilibrium sizes is reported. Finally, the effect of particle growth on the removal of cesium iodide aerosols by gravitational sedimentation is presented.     

氡室氡浓度调控系统的研究

为一个2.84m3的氡室研制了一套氡浓度控制系统。采用控制氡室与外界换气量的方法调节氡室中氡浓度。换气量采用短周期开关控制的方法-脉冲宽度控制法(PWM),换气周期为10min。采用了氡快速补充和快速排放装置。氡室中使用一个扩散式固体氡源。系统用计算机自动控制,氡浓度建立时间小于4h,控制平稳,长时间稳定性优于2%。     

混合模式低噪声3 kV高压直流电源设计

高压直流电源是电离室等核辐射探测器的关键部件。针对需要3 kV左右高压的电离室,本文研制了0～3 kV连续可调的低噪声、高效率、小体积及高稳定性的高压直流电源。该高压直流电源系统采用线性与开关混合模式设计,兼顾了转换效率与低噪声。核心部分升压转换部分采用线性罗耶谐振电路与高频变压器实现,保证足够低的高压电源输出纹波。罗耶谐振电路的供电电源则由边沿时间控制型超低噪声开关稳压器LT1534提供,从而实现了混合模式高压直流电源的设计。高压直流电源输出部分采用二阶RC滤波电路进一步降低了输出电压的纹波。实测输出电压范围为0～3 kV,静态功耗为0.4 W,3 kV输出时纹波为16.55 mV,由此可知该电源可用于低噪声的核辐射探测器供电场合。