冠醚萃取氯化铀(Ⅳ)的研究

本文研究了盐酸介质中多种不同结构冠醚对四价铀的萃取并求得分配比值。结果表明在以1,2-二氯乙烷为溶剂时二坏己基系列冠醚萃取铀(IV)最奸,且当水相酸度为8.0—8.5 M时分配比最大,其萃取能力依次为DCH-27-C-9>DCH-24-C-8>DCH-18-C-6>>DCH-30-C-10>DCH-21-C-7。用斜率法及等摩尔系列法证明,铀(IV)与五种二环己基冠醚萃合物的组成皆为1:2。本文还对萃取机理作了初步探讨。     

二环己基-18-冠-6萃取铀、钚和镅的研究

本文叙述了溶剂种类、酸度和冠醚浓度诸因素对二环己基18冠6(DCH 18 C 6)萃取铀、钚等元素的影响,着重研究了常量铀的萃取行为。结果表明,1,1,2—三氯乙烷作溶剂时,DCH18 C 6对微量铀或常量铀均能萃取。在硝酸体系形成的萃合物中,Pu(Ⅳ)和U(Ⅵ)与二环己基18冠6的分子比分别为2和1。DCH 18 C 6-1,1,2—三氯乙烷能够从含有U(Ⅵ)和U(Ⅳ)的3—5 M HCl溶液中单独萃取U(Ⅵ)而不萃取U(Ⅳ)。     

冠醚萃取法分离铀同位素的研究

本文研究了二环已基24冠8(DCH24C8)和二环已基18冠6(DCH18C6)的1,2-二氯乙烷溶剂萃取铀(VI)和铀(IV)的同位素效应,通过多级富集和贫化级联测定了铀同位素的平均单级分离因子,证实了在不变价态铀同位素分离体系中,冠醚体系的铀同位素效应显著大于其它体系。     

冠醚萃取钍(Ⅳ)的化学平衡及其萃合物的红外光谱

本文研究了数种冠醚的1,2-二氯乙烷溶液从硝酸、盐酸和苦味酸等水溶液中萃取钍的行为。在硝酸介质中,钍与二环己基-18-冠-6(DC18C6)或二环己基-24-冠-8(DC24C8)形成了萃合物Th(NO_3)_4·2L·HNO_3(L为冠醚)。其相应的萃取平衡常数(25℃)经测定分别为:K_(DC18C6)=3.98和K_(DC24C8)=6.30。 测定了萃合物Th(NO_3)_4·2DC18C6·HNO_3和Th(NO_3)_4·2DC24C8·HNO_3的红外光谱。差示光谱的特征吸收峰表明,金属离子和冠醚环上氧配位原子之间可能存在直接的键合,以及萃合物中NO_3根参与配位。     

冠醚萃取铀、钚、镅和铈的研究

本工作研究了二苯并—18—冠—6(DB 18 C 6)从硝酸介质中萃取铀、钚等元素的行为。纯硝酸溶液中萃取铀、钚的分配比很小,但当水相存在硝酸盐(例如NH_4NO_3)时,由于盐析效应,Pu(Ⅳ)、U(Ⅳ)和U(Ⅵ)的分配比均有很大增加。本文较系统地研究了DB 18 C 6作萃取剂时,水相酸度、DB 18 C6浓度、盐的种类及浓度对萃取的影响;求得在Pu的萃合物中溶剂化数为2。此外还比较了几种冠醚的萃取行为,发现苯并和其它二苯并冠醚对铀、钚、镅的萃取行为类似于DE 18 C6,也有盐析效应,二环已基—18—冠—6能从纯硝酸溶液中很好地萃取铀和钚。     

冠醚萃取同位素砹-211

为深入了解砹的化学性质,探索用冠醚作相转移催化剂来标记砹的化合物的可能性,采用冠醚二环己基-18-冠-6(DC18C6)于各种溶液中进行砹的萃取研究。 盐酸浓度变化显著影响DC18C6对~(211)At的萃取。随HCl浓度增加,萃取率急剧上升,在2mol·l~(-1)HCl时,萃取率可达99％。而用异丙醚萃取At需在8mol·l~(-1)HCl下进行,在2mol·l~(-1)     

四种二环己基系列的冠醚对UO_2(NO_3)_2的萃取

本工作研究了十五种不同结构的冠醚在硝酸介质中对UO_2(NO_3)_2的革取。结果表明:二环已基系列的冠醚对UO_2(NO_3)_2络合萃取的性能较其他冠醚为好,其中以二环己基—24冠—8和二环己基—27—冠—9对UO_2(NO_3)_2的萃取性能最好。还研究了水相酸度、平衡时间、反萃性能及铀浓度等因素对萃取的影响。经实验测定:二环己基—30—冠—10、二环己基—27—冠—9、二环己基—24—冠—8和二环己基—21—冠—7与UO_2(NO_3)_2所形成的萃合物组成比皆为1:1。所计算出的萃取平衡常数分别为:K_(DCH18C?)=11.5;K_(DCH21C7)=11.2;K_(DCH24C?)=18.2;K_(DCH27C?)=14.2;K_(DCH30C10)=12.9。     

关于冠醚对稀土元素萃取性能的研究

本文研究了十一种冠醚对稀土苦味酸盐的萃取。观察了冠醚的空腔大小、空间结构以及溶剂、对阴离子、水相酸度等对冠醚萃取性能的影响。不同冠醚萃取苦味酸镧能力的次序为:12-冠-4>单环己基-12-冠-4>苯并-12-冠-4;15-冠-5>苯并-15-冠-5>4-甲基苯并-15-冠-5;18-冠-6>苯并-18-冠-6>二苯并-18-冠-6;苯并-15-冠-5>苯并-18-冠-6>苯并-12-冠-4;二环己基-18-冠-6(DCC)的异构体A(I_A)>异构体A和B的混合物>异构体D(I_D)。 研究了三种冠醚对十五个单一稀土元素的萃取,测定了各元素的分配比(D)。logD对logC_L(C_L为冠醚总浓度)作图,其直线斜率对于苯并-15-冠-5和苯并-18-冠-6为2,对于DCC(I_A)为1(从La-Pr)和4/3(从Nd-Lu)。分配比随原子序数呈现有规律的变化,对于苯并-15-冠-5和苯并-18-冠-6,由La至Lu先增加,Sm处呈现最大,然后逐渐下降;而对于DCC(I_A),则由 La 至Lu依次降低。 得到了相邻稀土元素间的分离因数(β)。β_(Nd)~(Pr)随着DCC(I_A、I_D)浓度的降低而增大,最大分离因数可达3.66。     

二环己基-18-冠-6对铀(Ⅵ)的萃取

本工作研究了硝酸体系中十六种不同结构的冠醚对铀(Ⅳ)的萃取,萃取性能以二环己基系列的冠醚为最好。溶剂的介电常数大时铀(Ⅳ)的分配比增加,非极性溶剂所得的分配比很小。铀(Ⅳ)的分配比随水相中硝酸浓度增大而增加,在6.5MHNO_3时分配比最大,然后分配比又随硝酸浓度的增大而降低。该冠醚体系的动力学性质很好且很容易解络。初步实验结果表明,UO_2(NO_3)_2与二环己基—18—冠—6的络合物组成为1:1。另外,该络合物的红外光谱特征与文献中所述铀(Ⅳ)的配位键合情况符合。     

硝酸介质中二环己基18-冠-6对锶的萃取

利用冠醚二环己基-18-冠-6（DCH18C6）作为萃取剂在硝酸介质中对锶的萃取性能进行了系统研究,考察了稀释剂、硝酸浓度、振荡时间、温度对锶萃取的影响,结果表明,该萃取体系与硝酸的浓度有关,当萃取剂浓度为0.01mol/L,以1,1,2,2-四氯乙烷为稀释剂,硝酸浓度为1mol/L时,锶的萃取率可高达92%左右,利用纯水作为反萃剂,反萃率可达(99.56±1.7)%左右。该萃取反应动力学比较快,可在10min 达到平衡,热力学实验表明该萃取反应是一个放热反应。同时选择性萃取实验结果表明,冠醚二环己基-18-冠-6能有效地从多种离子共存的体系中选择性地萃取锶。     

Identification of radiation treatment of wheat （Triticum aestivum. L）and rice （Oryza sativa. L） samples using thermoluminescence of contaminating minerals

Food irradiation is gaining popularity worldwide and this technology is important to improve quality and reduce the post harvest losses of food. Because of the rapid commercialization of irradiated foods throughout the world, compliance of different regulations relating to use of technology in different countries and demand of consumers for clear labelling of irradiated foods, there is need for the development of analytical methods to detect radiation treatment of food. Among several methods studied so far, thermoluminescence （TL） is an important method that can be used to find out the irradiation history of food that contain even a very minute amount of dust particles. In this study, the irradiated and unirradiated wheat and rice samples were analyzed using the TL method. The samples were purchased from the local market of Peshawar and irradiated to radiation doses of 0.5 and 1.0 kGy using Co-60 gamma irradiator at the Nuclear Institute for Food and Agriculture （NIFA）, Peshawar. The mineral contaminants were isolated by jet water, ultrasonic treatment, and density gradient. TL glow curves of the isolated minerals from irradiated and unirradiated samples were recorded between the temperature ranges of 50-500℃ using a TL reader. Generally, the glow curves for irradiated samples showed much higher TL intensities （TL1） than the unirradiated samples. The results were normalized by rerradiation of mineral samples to gamma-ray dose of 1.0 kGy followed by determination of the second glow curves （TL2）. The ratio of the area of first glow curve to that of second glow curve （TL1/TL2） was calculated for selected temperature intervals and compared with the recommended values for unirradiated and irradiated samples. Finally, the shapes of the glow curves for irradiated and unirradiated samples were also analyzed. On the basis of these results （comparison of TL-intensities, TL1/TL2 ratios and shapes of the glow curves）, all the irradiated and unirradiated samples of wheat and rice were unequivocally identified.     

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。     

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.     

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.     

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.     

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.     

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.