中性水质中催化联氨除氧效果试验研究

介绍了中性水质中催化剂用量对催化联氨除氧效果的影响.试验条件为:温度10℃、20℃、30℃,初始溶解氧含量分别为10.0～10.8 mg/L(10℃)、8.2～8.6 mg/L(20℃)、7.0～7.4 mg/L(30℃),联氨用量为水中初始溶解氧含量的6倍、3倍.试验结果表明,催化剂用量为600～50 цg/L时,水中溶解氧含量均可降至100цg/L以下.     

含氧溶液中毒砂氧化溶解的XAFS研究

毒砂的氧化溶解是环境As污染的重要来源之一。本研究对毒砂的氧化反应过程及产物进行了研究。考察了不同参数:pH、溶解氧(Dissolved Oxygen,DO)对毒砂氧化反应的影响,利用X射线吸收精细结构(X-ray Absorption Fine Structure,XAFS)分析了毒砂氧化过程中As的形态转化。XAFS光谱学数据表明,pH=4时,毒砂发生较强的氧化反应,释放的As(V)被氧化过程中形成的铁氧化物吸附;pH=7时,毒砂氧化释放的As(III)被铁氧化物吸附,表面存在少量的类似雄黄(As S)的物质;而pH=9时,毒砂几乎不发生氧化,表面只存在少量的硫代亚砷。结果表明,pH是影响毒砂氧化的重要因素。中碱性条件下,毒砂氧化反应释放出的Fe快速形成了Fe的氧化物沉淀,包裹在毒砂的表面,阻碍毒砂继续氧化。     

固定化增殖氮循环细菌群SBR法净化富营养化湖水

依据太湖水体氮污染的特点,应用低温辐射技术预辐射引导玻璃态单体丙烯酸羟乙酯2－Hydroxyethyl acrylate（HEA）与聚乙二醇二甲基丙烯酸脂olyethylene glycol dimethacrylate(14G）共聚合制备高分子载体,并使用增殖细胞技术固经氮循环细菌群净化湖水。结果表明,富营养化湖水经固定化氮循环细菌群SBR工艺净化后,总氮下降75％,氨氮下降91．5％,COD下降75％,出水水质得到明显改善。研究结果还 显示,固定化氮循环细菌群的最适反应温度为28℃,溶解氧浓度对总氮的去除率有一定的影响,固定化菌在低温条件下表现出明显的耐受性。     

地浸采铀浸出液氧化沉淀法除铁研究

在氧化沉淀法去除铁的过程中,氧化反应分别在自然曝气、充气和除钙的条件下进行,对照结果进行分析,得出最佳的除铁配方,同时还着重对氧化反应速率及其影响因素(pH,Eh等)进行了探索性研究,为以后试验提供了一定的依据。     

X-750合金裂纹扩展速率的测量及SO_4~(2-)离子对裂纹扩展速率的影响

利用直流电压降方法(DCPD)测量X-750合金在空气中的疲劳开裂速率和高温高压水环境中的应力腐蚀裂纹扩展速率。介绍利用紧凑拉伸(CT)试样测量裂纹扩展速率的方法。基于滑移-氧化膜破裂-氧化模型,分析裂纹尖端特殊水化学环境形成的原理和过程,探讨水中溶解氧和SO42-离子在该环境形成过程中所起的作用。     

冷变形316不锈钢在高温水中的应力腐蚀开裂行为

对不同冷变形量的核级316和316L不锈钢在高温水中的应力腐蚀开裂(SCC)行为进行了研究。通过试验,对溶解氧、氯离子和温度对裂纹扩展速率的影响进行了深入探讨和分析。试验结果显示,溶解氧和氯离子能明显加快材料的应力腐蚀开裂速率。当水化学条件一致时,325℃时的裂纹扩展速率较288℃时的裂纹扩展速率高。     

N2气氛下氨水溶液γ辐射分解行为

某些压水堆中使用氨及其分解产生的H₂抑制H₂O₂、O₂和·OH等氧化性物种的浓度,在保持一回路的还原性化学环境的同时调节冷却剂pH,以减轻结构材料的腐蚀。本工作为了研究脱氧氨水溶液在辐射场中的分解行为,针对其在γ场中的辐解过程进行了实验研究,重点考察了N₂压强、气相与液相体积之比和温度对氨水溶液辐解的影响,测定了剩余氨、H₂和氮氧化物(NO₂^-和NO₃^-)的浓度及溶液的pH。结果表明：N₂压强(0.5～5.0 MPa)及气液体积比的变化未对氨的分解和氮氧化物的生成造成影响,吸收剂量为28.8 kGy时,辐解产生的氮氧化物浓度约为1 mg/L,但N₂压强和气液体积比的增加会显著降低H₂的浓度。温度由25℃升至200℃时,氨的分解过程将大幅放缓,吸收剂量为14.4 kGy时,30 mg/L氨水中氨的分解比例由...     

纳米零价铁去除溶液中U(Ⅵ)的还原动力学研究

采用液相还原法制备纳米零价铁（nZVI）,用来去除溶液中的U(Ⅵ),讨论了溶液pH值、nZVI质量浓度、接触反应时间和温度对去除效果的影响,并从nZVI对U(Ⅵ)的还原角度探讨了还原动力学规律。研究结果表明：nZVI对溶液中的U(Ⅵ)有很好的去除效果,其去除过程包括还原沉淀和吸附,其中还原过程符合准一级还原动力学模型;溶液pH值对去除效果有明显的影响,在溶液pH值为5.0时,去除率达到最大值96.27%。温度对去除效果有一定的影响,表观速率常数k_obs随反应温度的升高而增大,还原速率与反应温度的关系符合Arrhenius定律,反应活化能E_a为16.54 kJ/mol,低于一般化学反应的活化能（60～250 kJ/mol）,表明该反应较易进行。     

核级石墨失重率对其氧化速率的影响

采用热重分析方法研究600⁷50℃温度范围内IG-110核级石墨在空气中的氧化行为,分析失重率对其氧化速率的影响。利用随机孔隙模型拟合了IG-110、H-451、NBG-18及NBG-10等4种核级石墨的结构参数,并确定了各自的失重率影响因子表达式。结果表明,随着氧化反应的进行,核级石墨的氧化速率随失重率的增大呈现先增大后减小的趋势,氧化速率的最大值出现在30%750℃温度范围内IG-110核级石墨在空气中的氧化行为,分析失重率对其氧化速率的影响。利用随机孔隙模型拟合了IG-110、H-451、NBG-18及NBG-10等4种核级石墨的结构参数,并确定了各自的失重率影响因子表达式。结果表明,随着氧化反应的进行,核级石墨的氧化速率随失重率的增大呈现先增大后减小的趋势,氧化速率的最大值出现在30%⁴0%失重率范围。使用随机孔隙率模型可以较好地模拟失重率对氧化速率的影响,其中石墨结构参数随核级石墨平均粒径的增加而减少。     

低温辐射引发聚合甲基丙烯酸β-羟乙酯固定化葡萄糖氧化酶

本文研究在-78℃下,~(60)Coγ辐射引发亲水性单体甲基丙烯酸β-羟乙酯(HEMA)聚合固定化葡萄糖氧化酶(GOD),实验结果证明,控制辐射总剂量不超过1×10~4Gy,对葡萄糖氧化酶的活力损伤极微。载体HEMA浓度取为50％,包埋量是1.0ml GOD/10ml缓冲溶液(pH为5.6,0.06 mol/L磷酸缓冲液),可以得到既有弹性,又具有保存活力高的葡萄糖氧化酶固定化圆珠。辐照聚合HEMA温度越低,保存活力愈高。反应底物pH试验判明,固定化葡萄糖氧化酶的最适pH值与自然葡萄糖氧化酶的最适pH值一样,不过固定化葡萄糖氧化酶比自然酶更广泛适应于pH值的变化。固定化葡萄糖氧化酶动力学实验结果:米氏常数为k'm=1.42×10~(-2)mol比自然酶km=1.0×10~(-2)mol略高,说明了反应底物的扩散速度受到了一定的限制。活化能测定是13.7kJ/mol。     

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.     

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.     

微型X射线管空气比释动能和能谱的测量

为研究微型X射线管的特性,通过电离室测量光管出射口30 cm远处的空气比释动能,使用高纯锗探测器分别测量了Ag过滤和Cu过滤下的X射线能谱。结果表明,空气比释动能随电流的增加有线性增加的趋势,能谱图明显的观察到银的两个特征X射线。完成了微型X射线管空气比释动能和能谱的测量方法以及实验测量的工作,为微型x射线管下辐射质的建立提够了条件基础。     

Gamma-ray attenuation technique for measuring void fraction in horizontal gas-liquid two-phase flow

The measurement of void fraction is of importance to the oil industry and chemical industry. In this article, the principle and mathematical method of determining the void fraction of horizontal gas-liquid flow by using a single-energy γ-ray system is described. The γ-ray source is the radioactive isotope of 241Am with γ-ray energy of 59.5 keV. The time-averaged value of the void fraction in a 50.0-mm i.d. transparent horizontal pipeline is measured under various combinations of the liquid flow and gas flow. It is found that increasing the gas flow rate at a fixed liquid flow rate would increase the void fraction. Test data are compared with the predictions of the correlations and a good agreement is found. The result shows that the designed γ-ray system can be used for measuring the void fraction in a horizontal gas-liquid two-phase flow with high accuracy.