金属氢化物柱内氢同位素的快速排代

为寻找能实现快速排代的金属氢化物,对ZrCo、LaNi5、LaNi4.7Al0.3和Pd材料的填充柱进行了氢氘间的一维排代实验研究,结果表明排代速率与温度、固相比表面积及分离因子等因素有关;室温下Pd氢化物具有最快的排代速率,其次是LaNi5,LaNi4.7Al0.3,ZrCo.通过微观的气-固交换过程分析,定性揭示了影响排代速率的因素和条件.高流速排代实验证明,用Pd作柱填充材料,可以实现氢同位素的快速排代.     

LaNi5和LaNi4.7Al0.3柱内氕氘排代模拟

假设排代过程受表面反应控制和气相中H2与D2快速达到反应平衡,建立了流速和温度恒定条件下LaNi5和LaNi4.7Al0.3柱内氕排代氘的一维数学模型。该模型基于分子碰撞理论,考虑了分离因子对氢同位素排代的影响。模型中的气-固相同位素交换几率为可变参数,其余参数使用了文献值或实验值。计算了LaNi5和LaNi4.7Al0.7柱内氕排代氘及LaNi5柱内氘排代氕过程中流出端氢同位素各组分丰度随时间的变化关系并与实验结果进行了对照。结果表明:当同位素交换几率为2.96×107时,根据数学模型获得的排代流出曲线与实验结果具有良好一致性,该模型可恰当描述金属氢化物柱内氢同位素的排代行为。     

聚苯乙烯-二乙烯基苯氢氘排代的热力学计算

聚苯乙烯-二乙烯基苯(SDB)是氢同位素分离技术中气-液交换反应重要的疏水催化剂载体.用密度泛函B3P86方法和基函数6-311G进行全电子计算,获得了SDB疏水官能团分子苯乙烯的基态电子状态、基态能量、离解能和几何参数.计算了苯乙烯上H、D排代反应的焓变、熵变和吉布斯函数变化,以及反应的平衡常数和气体压力比.计算结果表明,SDB上氘排代氢的反应有可能发生,但进行的程度较低,且随着反应温度的提高,这种排代将更难进行.同时,计算表明氢氘排代更易发生在苯环上,而乙烯基上的排代相对困难.     

~2H和~3H标记四氢原小檗碱的合成

四氢原小檗碱是一类天然存在的生物碱,新近研究表明其左旋异构体是脑内多巴胺受体 的拮抗剂,而右旋体则极可能是多巴胺的排空或释放剂。为了研究它们的氚标记化合物的生物活性,我们用NaBH_4还原法制备了氚代位置在C_8和C_(14)位上的三种四氢原小檗碱,即氘代四氢小檗碱(THB-d_2),氘代四氢巴马汀(THP-d_2)和氘代千金藤立定(SPD-d_2)。氘代物的质谱显示它们的分子离子峰均比非氚代物增加2,RDA产生的两碎片峰均比非氘代物增加质量1。故可推定反应中分子上了两个氘原子,氘代位置只能分别在C_8和C_(18)位上。从氘代物的′H-NMR看,C_(14)位质子信号消失,表明该位置为氘取代。C_8位质子信号由非氘代物的两组二重峰(AB型)变成氘代物的两个单峰,每单峰积分为0.5H,两单峰具有较大的化学位移值之差(Δδ=0.7),表明B/C环应为反式稠合。IR在2800cm~(-1)处Bohlmann带亦可作证。对于C_8位置质子信号可解释为由于氘负离子首先还原平面型季铵阳离子成二氢化物时没有优势进攻面,氘在横或竖键上的分布几率均等,故C_8-H两单峰积分各为0.5H。     

金属氢化物柱内氕氘间的排代

在ZrCo,LaNi5,LaNi4 .7Al0 .3和Pd等常用金属的氢化物上 ,进行了气 固间氕氘的一维相互排代实验 ,结果表明 :排代效果与温度、气相流速、固相比表面积及分离因子等因素有关 ;室温下Pd氢化物具有最好的排代性能 ,其次是LaNi5,LaNi4 .7Al0 .3,ZrCo。理论研究表明 ,气 固界面的同位素交换规律决定排代效果 ,排代流出曲线可以用塔板理论模型来描述 ,塔板高度是排代效果优劣的标志。决定塔板高度的首要因素是交换平衡程度 ;同等交换平衡程度下 ,氢同位素效应对板高有重要影响。     

钯-氢体系中氢氘的排代研究

研究了一维排代条件下,Pd-H体系中气-固相间氢-氚的相互排代性能。实验结果表明：对于较细的钯颗粒（≈0.15mm),室温（≈22℃）下气体线流速在2.0～8.5cm/s范围内具有较理想的排代效果,表现反应速率主要取决于气-固界面的化学速率;在22～75℃范围内,温度对排代效果的影响较小,当温度降至10℃时,氢氚在固相内的扩散速率较小,排代效果显著变差。     

~2H和~3H标记四氢原小檗碱的制备

本文报道由相应的原小檗碱季铵盐经NaBD_4还原方便地制得三个氘代四氢原小檗碱同类物。氘代位置及产物构型经质谱、核磁共振和红外光谱得到证实。类似地还制得具有较高比放射强度和放化纯度的氘标记四氢小檗碱和千金藤立定。     

Ti-Mo互扩散界面吸氢同位素效应的离子束分析研究

为探究Ti-Mo互扩散对金属吸氢的影响,本文采用离子束分析方法对Ti-Mo薄膜的膜-基互扩散界面的吸氢同位素（H和D）效应进行了研究。通过氩离子刻蚀减薄的方法有效降低了表面碳、氧杂质对样品吸氢的影响。吸氢结果表明,对于表面洁净的样品,氢化后固相中氢或氘的浓度均沿着深度随钼原子含量的增加而减小。在单一气体吸氢实验中,氢原子浓度减小的趋势较氘原子缓慢;而在氢氘混合气体吸氢实验中,当容器中的氢氘压强比p(H2)∶p(D2)≥05∶1时,固体中氘氢浓度之比随钼浓度的增加而降低,但当p(H2)∶p(D2)<05∶1时,氘氢浓度之比随钼浓度的增加而升高。因此,由于Ti Mo界面的互扩散,吸氢出现了显著的氢同位素效应,钼的存在不利于体系对氢同位素气体的吸收。     

氢同位素催化交换过程影响因素研究

氢-水催化交换反应是研究氢同位素分离的重要手段,对反应过程中各影响因素的研究是氢同位素分离工作中的重要内容。在自行设计的不锈钢催化交换柱中,装填一定体积比的疏水催化剂与亲水填料,进行H-D体系气液催化交换实验。观察反应温度、气液摩尔比、不同原料水氘浓度对传质系数的影响,讨论了气体流速对床层压力降的影响情况。结果表明,不同气液比下,反应温度为45°C时传质系数最高。传质系数随原料水氘浓度(5.05 20.1)×10 3增加而降低,传质系数在0.58 1.17和2.65 3.56随着气液摩尔比而增加,催化交换柱床层压力降随气体流速而增加。研究发现,反应温度、气液摩尔比和氘浓度等因素均会影响氘的传质系数。     

氘重氧水液相催化交换法氢正常化工艺研究

液相催化交换法是有效的氢同位素分离方法之一,传统电解法进行氘重氧水氢正常化安全风险大,生产成本高,为此利用液相催化交换法对含氘重氧水进行除氘实验。结果表明,反应温度在30~70 ℃内,随着温度升高,含氘重氧水除氘过程的总体积传质系数（Kya）值先变大后变小,当温度大于60 ℃后,总体积传质系数Kya值逐渐变小,最优反应温度为60 ℃;气液比（摩尔比）在0.5~3.0之间,随着气液比增加,含氘重氧水除氘过程的Kya值愈大,含氘重氧水除氘效果越好,但过大的气液比会引起气液夹带甚至导致液泛,降低反应效率。实验结果可为开展高氘浓度氘重氧水液相催化交换法氢正常化工艺研究提供依据。     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.