水相中喹啉的辐解机理研究

利用纳秒级脉冲辐解技术对多种条件下喹啉水溶液的氧化还原机理进行了研究,并对瞬态粒子的主要吸收峰作了归属。探讨了喹啉在羟基、氢自由基、水合电子作用下所产生的瞬态粒子的生成、衰减行为。研究表明,·OH与喹啉在碱性条件下反应生成OH-加合物,速率常数为5.5×109L/mol?s?;在酸性条件下喹11啉先与氢离子反应生成喹啉阳离子,再与羟基发生加成反应,反应速率常数为7.9×109L/mol?s?;在中性条11件下和在碱性条件下反应相似,反应速率常数为7.2×109L/mol?s?;喹啉与水合电子反应生成的喹啉阴离子11自由基,其反应速率常数为7.05×109L/mol?s?;喹啉还可以与氢自由基的发生亲电加成反应。11     

2-氯酚水溶液的脉冲辐解研究

利用脉冲辐解技术对 2-氯酚水溶液在多种条件下的降解行为进行了详细研究。对瞬态光谱中的主要吸收作了归属,并考察了这些瞬态产物的生成和衰减动力学。研究表明,在不同 pH 值下,2-氯酚与?OH 的反应途径不同:中性条件下主要生成羟基加成物,其生成速率常数为 8.3×109dm3?mol-1?s-1;碱性条件下,则主要发生电子转移形成 2-氯代酚氧基,同时存在羟基加成物脱 HCl 和脱 OH-过程。?N3与 2-氯酚发生单电子氧化,形成 2-氯代酚氧基。?H 与 2-氯酚发生加成反应生成环己二烯类氢加成物,其速率常数为 2.5×109dm3 ? mol-1 ? s-1。eaq 与 2-氯酚发生电子转移,生成羟苯基和氯离子,碱性条件(pH=11)和中性条件下的速率 -常数分别为 3.5×108 dm3?mol-1?s-1和 2.2×109 dm3?mol-1?s-1。该结果有助于人们进一步了解氯酚降解的本质,从而为该类化合物的降解处理提供了理论基础。     

辐射技术用于染料废水的脱色与降解

详细阐述了染料废水辐射降解的机理、影响因素和工程应用,为后续研究和工业应用提供参考.经辐照过的染料溶液所产生的·OH、eaq-和H·具有很高的活性,可以和染料分子发生氧化和还原反应,使“-N=N-”和“-C=C-”断裂. OH为强氧化剂,可以直接氧化染料分子并将其降解.eaq-是强还原剂,可迅速脱去染料的颜色,但对脱色...     

二氟沙星在乙腈溶液中的激光光解研究

采用纳秒级激光光解瞬态研究技术,以乙腈作为溶剂,研究在355 nm激光作用下产生二氟沙星(DFX)激发三重态,并利用能量转移的实验进一步研究了二氟沙星激发三重态的性质。结果显示,萘普生和二氟沙星的二元体系在355 nm激光作用下,二氟沙星首先被激发为其激发三重态(580 nm),二氟沙星激发三重态与萘普生发生激发能转移,产生萘普生激发三重态(440 nm)。通过能量转移的方法确定了二氟沙星在乙腈溶剂中产生的激发三重态在最大吸收波长580 nm处的摩尔消光系数为8,900 dm3/mol·cm。通过改变二氟沙星的浓度测得其激发三重态在乙腈体系中的自衰变速率常数和三重态平均寿命(τ)分别为5.39×106 s-1和2.8μs。     

对-硝基苯甲酸的光解行为探讨

以对-硝基苯甲酸为模型,探索两个取代基处于对位而同时不溶于水但溶于有机溶剂的芳香族硝基类有机物的光解行为,为有效降解此类化合物提供实验方法与理论支持。通过266nm激光光解和254nm紫外光降解两种手段对对-硝基苯甲酸的光解行为进行了研究,考察了不同体系对对-硝基苯甲酸光解行为的影响,并获得了相应的ns级激光光解瞬态吸收光谱及紫外光降解效果,为其降解机理研究奠定了基础。通过实验发现,在激光光解条件下,310nm附近有激发三线态的生成;紫外光难以直接降解对-硝基苯甲酸,但UV/H2O2却可提高其降解效率,经分析,认为H2O2在紫外光作用下产生的.OH起到了关键性作用。     

甲基肼水溶液的脉冲辐解研究

利用脉冲电子束进行甲基肼水溶液的脉冲辐解研究,对其瞬态光谱中的主要吸收峰作了归属,并初步考察了这些瞬态物种的生长、衰减等行为.结果表明,·OH与甲基肼反应生成CH3·NNH2,速率常数为(2.4±0.1)×1010mol-1·L·s-1;enq-与甲基肼反应生成CH3·NHNH2自由基,速率常数为(2.7±0.2)×1...     

氯代有机污染物辐照脱氯的研究进展

本工作对电离辐射引发的典型氯代有机污染物的脱氯降解机理进行了综述,重点回顾了氯酚、多氯联苯、三氯乙烯和四氯乙烯辐照脱氯降解的研究现状.氯酚在氧化条件下与羟基自由基(·OH)反应首先形成·OH加成物,然后逐步脱氯;在还原条件下水合电子(e-aq)与氯酚直接发生选择性反应脱氯,生成苯酚和氯离子.多氯联苯在有机溶剂中的辐照降...     

X射线相衬成像用于生物碱沉淀研究的可行性

生物碱与一些特殊的试剂作用生成沉淀。这些反应可用于生物碱的检测和精制。本文分别在同步辐射装置和微聚焦X射线成像系统上用X射线相衬成像(XPCI)方法研究了三种不同类型的生物碱沉淀的结构。研究结果显示：在Hager试剂作用下,有机胺类的秋水仙碱沉淀呈针状,吡啶类的槟榔碱沉淀呈胶团状,异喹啉类的小檗碱沉淀呈花瓣状。与目测或在光学显微镜下观察到的形态有很大差别。为今后用XPCI方法研究更复杂的化学反应体系提供参考和依据。     

二甲基羟胺水溶液的脉冲辐解研究

利用脉冲电子束进行二甲基羟胺(DMHAN)水溶液的脉冲辐解研究,对其瞬态光谱中的主要吸收峰作了归属,并初步考察了这些瞬态物种的生长、衰减等行为。研究结果表明,·OH与DMHAN反应生成(CH3)2NO·自由基,测得速率常数为(4.5±0.3)×109mol-1·L·s-1;eaq-与DMHAN反应生成(CH3)2N·自由基,测得速率常数为(1.3±0.04)×109mol-1·L·s-1。     

硫辛酸清除自由基的反应动力学研究

利用脉冲辐解和激光光解瞬态吸收光谱装置,研究了硫辛酸清除活性氧自由基（ROS）的反应机理,获得涉及反应的瞬态吸收光谱和反应速率常数,测得硫辛酸清除OH,eaq,CO3^-,SO4^-,Br2^-的反应速率常数分别为7．4×10^9、1．3×10^10、9．8×10^8、2．3×10^9、2．0×10^9L·mol^-1·s^-1,并对可能的反应机理进行了探讨。结果表明,硫辛酸能有效地清除活性氧自由基,是个高效的抗氧化剂。     

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.