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1.
本文开发了一种新的高效液相色谱(HPLC)法,并应用于地质材料中U和Th含量的测定。首先用HF-HClO_4和HCl浸提液在螺旋盖Savillex烧杯中酸消解岩石样品,然后Th和U用定量的两步离子交换法从地质基体中分离出来,最后采用HPLC进行元素测定。Th和U在反相交换柱上用梯度淋洗,10min即互相分离,而且剩余基体元素以α-羟基异丁酸(HIBA)络合物形式与Th和U分离。在与偶氮胂Ⅲ在线后置柱反应之后,Th和U的测定是用可见分光光度测定法完成的。Th和U的检测限分别约为30×10~(-12)和100x10~(12)(或约0.75×10~(-9)和约2.5×10~(-9),用100mg岩石样品)。 HPLC技术已应用于评价分析特性的9种国际参考样品和3种性能良好的管理样品分析。分析样品中Th和U的浓度范围为<10×10~(-9)~>10×10~(-6),HPLC数据与火花源质谱、电感耦合等离子体(ICP)和同位素稀释热电离质谱分折的数值完全吻合。对Th和U含量分别高于50×10~(-9)和5×10~(-9)的测量,方法精密度在1σ置信水平时分别好于±2%和±5%。  相似文献   

2.
本文研究了二辛基硫醚的萃取性能并将其用于地质样品中痕量银的中子活化分析(NAA)。将地质样品于反应堆(中子通量为(4-7)×10~(13)n/cm~2·s)中照射200h,冷却一个月以上,用HF-HNO_3-HClO_4分解样品,于1N HNO_3介质中用0.2M二辛基硫醚-氯仿溶液萃取,有机相作Ge(Li)γ谱分析,用相对比较法求出样品中银含量。化学产额为92%。分析了水系沉积物、岩石和土壤标样,测得银的含量范围为0.023-4.35ppm,实际样品的测定精密度在±15%以内。  相似文献   

3.
我们用仪器中子活化分析法测定了天然牛黄和人工牛黄中20个微量元素的含量。 天然牛黄样品用的是京津地区的京牛黄及进口牛黄两种。人工牛黄样品用的是北京药店现在销售的商品。用牛肝SRM-1577检验了实验方法准确度。测得元素的放射性统计误差为10~30%。  相似文献   

4.
采用仪器中子活化分析法测定了各种地质样品中20多个元素的含量。为了检验方法的准确度和精密度,分析了美国国家地质局的标准物质USGS-AGV-Ⅰ、USGS-BCR-1及美国国家标准局的NBS-1632煤粉,准确度和精密度的误差均小于15%。 用仪器中子活化分析法测定了日喀则蛇绿岩中稀土元素含量,通过对稀土元素地球化学特征的分析,我们认为日喀则蛇绿岩在地球化学性质方面相似于大洋中脊拉斑玄武岩,它们可能是形成于特提斯洋脊。  相似文献   

5.
本文叙述利用60mg月岩样品测定包括14种稀土在内的36种元素的含量。称取20.00mg月岩样品密封于聚乙稀薄膜小袋里,利用原子能研究所游泳池式反应堆的水平孔道,由气动快速辐照装置,对样品、标准和国际标样W-1分别与C1监察器在中子通量为3×10~(12)n·cm~(-2)·s~(-1)处辐照5分钟,冷却5分钟后测定A1、Ti、V、Ca;冷却1小时后测定Dy、Mn;冷却10小时后测定Eu、Na;冷却30小时后测定Sm。将上述的20.00mg样品转移到小铝盒内,称取42.10mg的W-1标样装入小铝盒内与制备好的中、长寿命核素的标准包在一起,在堆的垂直孔道中中子通量为2×10~(13)n·cm~(-2)·s~(-1)处照射20小时;冷却5天、10天和20天后分别测定Na、La、Sm、Ho、Eu、Yb、Hf、Cr、Fe、Sc、Co、Lu和Tb。冷却50天后进行放化分离,然后测定Tm、Ta、Gd、Ce和Zn。第二次照射取月岩样42.10mg,W-1标样64.90mg和制备好的标准,在中子通量为2×10~(13)n·cm~(-2)·s~(-1)处辐照40小时,冷却12小时后取出。样品用1mlHClO_4 2ml  相似文献   

6.
苏联利用动力堆中子活化分析岩石和矿石中的金及其伴生元素含量。被辐照的样品置于电离室备用孔道。该孔道位于活化区外石墨反射层,直径50mm,此处最大热中子流密度为10~9cm~(-2)·s~(-1),温度80—90°C。样品能在这里长时间(几昼夜)被辐照。利用中子活化分析方法测定金基于放射性俘获的~(197)Au (n,γ)~(193)Au (T1/2=65h)反应和记录的41~2KeVγ辐射能。样品破碎到200目,其含金范围为2×(10~(-5)—10~(-3))%。为定量测量利用标准样P3C-1和P3C-2,其含金量分别为5.21×10~(-3)和9.4×10~(-5)%。被辐照的样品放入聚乙烯安瓿中(直径和高分别为40和20mm),样品质量为15—20g。不仅用全谱中子流还要用镉上中子进行辐照(在后一种情况下安瓿被厚度为O.5mm的镉屏围绕。)。辐照时间与金含量多  相似文献   

7.
本法采用237—季铵萃取树脂,利用萃取色谱分离技术,将陶瓷UO_2芯块粉末中铀与待测杂质元素在6.5mol/L HNO_3介质中定量分离后,用975型ICP直读光谱仪同时测定流出液中Al、Ba、Co、Ta、Ti和V,取样300mg时,测定下限为0.016×10~(-6)-0.25×10~(-6),RSD<7.5%。分析结果均落在标准值的置信区间内。  相似文献   

8.
本文叙述了用TBP萃取色层法分离后,用水平式ICP-AES法测定U_3O_8中25种杂质元素的分析方法。U_3O_8样品转化为硝酸铀酰后,采用以TBP萃淋树脂为固定相、5mol/LHNO_3为流动相的萃取色层法使杂质元素与铀基体分离,杂质流出液用水平式ICP为激发光源的发射光谱分析法直接测定。取样0.3g,所有元素的测定下限在0.04—5ppm之间。方法的重加回收率在82—121%之间。相对标准偏差在±13%以内。  相似文献   

9.
研究用HCl溶解金属铍,在HNO3介质中用磷酸二丁酯(DBPA)-苯萃取,将铍与待测杂质元素分离,用ICP-AES法测定Co、Mn、Mg、Cr、Si、Cu、Al、Ni 8种杂质元素的含量.取样量为40 mg时,上述杂质元素的测定范围在5.0×10-4%~0.1%之间,方法回收率为95%~104%,相对标准偏差优于10%(n=6).  相似文献   

10.
磷尾矿中稀土元素含量是解释矿物的形成和发展的最好工具,所以准确测定其含量意义很大,磷尾矿成分复杂、干扰元素多、必须采取化学分离才能测定14个稀土元素。分离存在手续复杂、消耗时间长以及洗脱体积大等缺点。本文着重研究了用化学分离去干扰元素进行稀土元素的测定。称20-25mg样品与待测元素标准包装好后在热中子通量为(3—5)×10~(13)n/cm~2·s下辐照20小时。样品辐照后定量转移到白金坩埚中加载体、混酸溶解蒸发近干,加  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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。  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
为对自制的活性面积高达1 000 cm2的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的241Am点源及活性区面积为10 cm×15 cm的大面积241Am和90Sr-90Y源对其进行计量学性能测试。结果表明:计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm2;所得241Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;90Sr-90Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。  相似文献   

18.
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.  相似文献   

19.
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.  相似文献   

20.
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.  相似文献   

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