The Effect of Air Plasma on Sterilization of Escherichia coli in Dielectric Barrier Discharge

In this work,a Dielectric Barrier Discharge (DBD) air plasma was used to sterilize Escherichia coli (E.coli) on the surface of medical Polyethylene Terephthalate (PET) film.The leakage of cellular DNA and protein by optical absorbance measurement at 260 nm and 280 nm,together with transmission electron microscopy (TEM) about cell morphology were performed after sterilization to analyse inactivation mechanisms.The results indicated that the DBD air plasma was very effective in E.coli sterilization.The plasma germicidal efficiency depended on the plasma treatment time,the air-gap distance,and the applied voltage.Within 5 min of plasma treatment,the germicidal efficiency against E.coli could reach 99.99%.An etching action on cell membranes by electrons,ions and radicals is the primary mechanism for DBD air plasma sterilization,which leads to the effusion of cellular contents (DNA and protein) and bacterial death.     

Study on the Generation Characteristics of Dielectric Barrier Discharge Plasmas on Water Surface简

A new contact glow discharge electrode employed in this study. Because of the strong field the electrode and the water surface, glow discharge on the surface of water was designed and strength in the small air gap formed by plasmas were generated and used to treat waste water. The electric field distribution of the designed electrode model was simulated by MAXWELL 3D~ simulation software, and the discharge parameters were measured. Through a series of experiments, we investigated the impact of optimal designs, such as the dielectric of the electrode, immersion depths, and curvature radii of the electrode on the generation characteristics of plasmas. In addition, we designed an equipotential multi-electrode configuration to treat a Methyl Violet solution and observe the discoloration effect. The experimental and simulation results indicate that the designed electrodes can realize glow discharge with a relative low voltage, and the generated plasmas covered a large area and were in stable state. The efficiency of water treatment is improved and optimized with the designed electrodes.     

Experimental Study on Inactivation of Bacterial Endotoxin by Using Dielectric Barrier Discharge

The low-temperature plasma （LTP） generated by dielectric barrier discharge （DBD） was used to sterilize the E.coli endotoxin, which is usually difficult to kill ...     

The Experimental Investigations of Dielectric Barrier Discharge and Pulse Corona Discharge in Air Cleaning

The dielectric barrier discharge (DBD) and pulse corona discharge(POD) plasmagenerator was used to remove NHa, H2S, C7H8 etc. from atmosphere. The principle and charac-teristic of the two ways was discussed in the article. The test shows the result of PCD is betterthan that of DBD.     

快中子辐照对枯草芽孢杆菌的灭菌效果研究

利用快中子脉冲堆(Chinese Fast Burst ReactorⅡ,CFBR-Ⅱ)产生的快中子,采用枯草芽孢杆菌黑色变种为材料,考查了中子辐射灭菌效果及剂量、剂量率、辐照温度、照射状态等辐射灭菌影响因素.结果表明,在剂量率为7.4 Gy/min时的D10值为384.6Gy,中子剂量与存活芽孢对数满足y=-0.0026x 10.462的函数关系;在剂量为800Gy时,剂量率与存活芽孢对数满足y=7.7414X-0.0834的函数关系;升高温度有利于中子辐射灭菌;中子辐照不同状态芽孢,其存活率为:菌片＞粉末＞液体.     

Investigation on the Micro-Discharge Characteristics of Dielectric Barrier Discharge in a Needle-Plate Geometry

In this study, a dielectric barrier discharge device with needle-plate electrodes was used to investigate the characteristics of the micro-discharge in argon at one atmospheric pressure by an optical method. The results show that there are two discharge modes in the dielectric barrier discharge, namely corona mode and filamentary mode. The corona discharge only occurs in the vicinity of the needle tip when the applied voltage is very low. However, the filamentary discharge mode can occur, and micro-discharge bridges the two electrodes when the applied voltage reaches a certain value. The extended area of micro-discharge on the dielectric plate becomes larger with the increase in applied voltage or decrease in gas pressure. The variance of the light emission waveforms is studied as a function of the applied voltage. Results show that very short discharge pulse only appears at the negative half cycle of the applied voltage in the corona discharge mode. However, broad hump (about several microseconds) can be discerned at both the negative half cycle and the positive half cycle for a high voltage in the filamentary mode. Furthermore, the inception voltage decreases and the width of the discharge hump increases with the increase in applied voltage. These experimental phenomena can be explained qualitatively by analyzing the discharge mechanism.     

Study of Humidity Effect on Benzene Decomposition by the Dielectric Barrier Discharge Nonthermal Plasma Reactor

The humidity effects on the benzene decomposition process were investigated by the dielectric barrier discharge(DBD) plasma reactor.The results showed that the water vapor played an important role in the benzene oxidation process.It was found that there was an optimum humidity value for the benzene removal efficiency,and at around 60% relative humidity(RH),the optimum benzene removal efficiency was achieved.At a SIE of 378 J/L,the removal efficiency was 66% at 0% RH,while the removal efficiency reached 75.3% at 60% RH and dropped to 69% at 80% RH.Furthermore,the addition of water inhibited the formation of ozone and NO_2 remarkably.Both of the concentrations of ozone and NO_2 decreased with increasing of the RH at the same specific input energy.At a SIE of 256 J/L,the concentrations of ozone and NO_2 were 5.4 mg/L and 1791 ppm under dry conditions,whereas they were only 3.4 mg/L and 1119 ppm at 63.5%RH,respectively.Finally,the outlet gas after benzene degradation was qualitatively analyzed by FT-IR and GC-MS to determine possible intermediate byproducts.The results suggested that the byproducts in decomposition of benzene primarily consisted of phenol and substitutions of phenol.Based on these byproducts a benzene degradation mechanism was proposed.     

Performance of Dielectric Barrier Discharge Reactors on Elemental Mercury Oxidation in the Coal-Fired Flue Gas

The oxidation of elemental mercury （Hg~） by dielectric barrier discharge reactors was studied at room temperature, where concentric cylinder discharge reactor （CCDR） and surface discharge plasma reactor （SDPR） were employed. The parameters （e.g. Hg^0 oxidation efficiency, energy constant, energy yield, energy consumption, and O3 concentration） were discussed. From comparison of the two reactors, higher Hg^0 oxidation efficiency and energy constant in the SDPR system were obtained by using lower specific energy density. At the same applied voltage, energy yield in the SDPR system was larger than that in the CCDR system, and energy consumption in the SDPR system was much less. Additionally, more 03 was generated in the SDPR system. The experimental results showed that 98% of Hg^0 oxidation efficiency, 0.6 J·L^-1 of energy constant, 13.7 μg·J^-1 of energy yield, 15.1 eV·molecule^-1 of energy consumption, and 12.7 μg·J^-1 of O3 concentration were achieved in the SDPR system. The study reveals an alternative and economical technology for Hg^0 oxidation in the coal-fired flue gas.     

核电站排放水对周围水生生物影响的研究进展与展望

随着核能的开发与利用,核电站排放水对周围生态系统的影响愈发受到人们的重视,相关研究也逐渐增多。本文概述了秦山、大亚湾、Ignalina和Almaraz等4个核电站的相关研究,总结4 个核电站排放水对周围生态系统的影响。得出核电站排放水对水生生态系统的作用主要受水体稀释能力的影响。当排放水量较小,受纳水体的交互作用较强时,周围水体和生物中的放射性水平会随之降低,升温现象也不明显,反之,当排放水中的核素没有得到充分的稀释扩散时,其放射性水平会明显高于本底调查值,发生明显的蓄积现象,甚至产生辐射影响,排放口附近水温也会明显升高,导致恒温种鱼类和藻类的数量逐渐减少甚至最终消失,而暖水种则占据优势,逐渐成为群落的主体。此外,随着现代计算机技术的快速发展,利用大数据进行模拟计算,选择模式生物实验进行验证,将帮助人们更好地认识排放水对水生生态系统的影响,为核电环境影响评价提供参考,也有利于后续的核电发展。     

Influence of the Gas Mixture Ratio on the Correlations Between the Excimer XeCl Emission and the Sealed Gas Temperature in DIelectric Barrier Discharge Lamps

For dielectric barrier discharge lamps filled with various gas mixture ratios,the correlations between the excimer XeCl emission and the sealed gas temperature have been founded,and a qualitative explication is presented.For gas mixture with chlorine larger than 3%,the emission intensity increases with the sealed gas temperature,while with chlorine about 2%,the emission intensity decreases with the increase in the gas temperature,and could be improved by cooling water .However,if chlorine is less than 1.5% ,the discharge appears to be a mixture mode with filaments distributed in a diffused glow-like discharge,and the UV emission is independent on the gas temperature.     

临界实验装置水位外推达临界方法优化研究

带乏燃料的临界实验装置可用于开展乏燃料贮存相关的临界实验研究,考虑到其具有较高放射性,因此开展实验时最佳方法是水位外推达临界方法。目前该带乏燃料的临界实验装置尚未建成,遂使用与其堆芯结构、物理特性相似的铀棒栅轻水慢化临界实验装置开展水位外推达临界方法的模拟实验。在该实验中,由于水的屏蔽作用随水位上升不断加深导致无法得到正常的外推曲线。本文通过蒙特卡罗程序模拟外推过程,研究了中子源与探测器在不同的相对位置处中子计数率随水位变化的规律,给出了探测器与中子源的优化布置方案。此外,还提出一种以水位价值作为外推参数的外推方法,消除了水位高度外推时水位系数不均匀的影响,使得外推结果更准确。     

2009-2011年和2015-2018年阳江核电站外围 地表水、饮用水的90Sr放射性水平监测

采用国家标准《水和生物样品灰中锶-90的放射化学分析方法》萃取色层法/发烟硝酸沉淀法对阳江核电站运行前后其周围环境地表水、饮用水的⁹⁰Sr放射性水平进行了监测。监测结果表明,阳江核电站运行前后其周围环境地表水、饮用水中⁹⁰Sr活度浓度总体在同一水平,且与对照点⁹⁰Sr放射性水平相当。     

LOCA和SGTR事故下破口尺寸计算方法研究

事故状态下一回路破口的大小直接影响到核电厂的安全屏障,对破口大小进行评估是核反应堆安全分析的重要基础,也是电厂应急响应小组的主要任务之一。通常考虑流入和流出一回路流体的质量平衡,用来计算破口流率。本文在总结一回路流体质量平衡计算方法的基础上进行深入研究,提出利用安注(SI)流量动态平衡进行破口尺寸估算的方法,同时利用信息开发技术将两种方法的计算过程程序化。最后,通过与法国SESAME系统的破口计算结果进行对比分析,同时验证了压水堆失水事故(LOCA)和蒸汽发生器传热管破裂事故(SGTR)中两种计算方法的准确性。     

压力容器外部冷却系统冷却水池温度场的实验研究及分析

压力容器外部非能动冷却系统采用换料水池作为冷却水源。在浮升力驱动的自然循环流动作用下,冷却水池内会逐渐出现热分层现象。本实验基于先进压水堆压力容器外部冷却系统模拟装置REPEC实验回路,通过测量实验系统内冷却水箱的温度场空间分布,对冷却水池的热分层与混合现象、发展规律和主要影响因素进行了实验分析。结果表明：实验水箱内温度场分布差异主要表现在高度方向;循环流量是影响热分层的重要参数,而水箱工质初始温度的影响非常微弱;针对本实验的无量纲一维瞬态温度场方程分析表明,水箱内温度场的发展规律主要受对流传热控制。     

Research on the degradation mechanism of dimethyl phthalate in drinking water by strong ionization discharge

The degradation mechanism of dimethyl phthalate(DMP) in the drinking water was investigated using strong ionization discharge technology in this study. Under the optimized condition, the degradation efficiency of DMP in drinking water was up to 93% in 60 min. A series of analytical techniques including high-performance liquid chromatography, liquid chromatography mass spectrometry, total organic carbon analyzer and ultraviolet–visible spectroscopy were used in the study. It was found that a high concentration of ozone(O_3) produced by dielectric barrier discharge reactor was up to 74.4 mg l~(-1) within 60 min. Tert-butanol, isopropyl alcohol,carbonate ions(CO_3~(2-)) and bicarbonate ions (HCO_3~-) was added to the sample solution to indirectly prove the presence and effect of hydroxyl radicals(·OH). These analytical findings indicate that mono-methyl phthalate, phthalic acid(PA) and methyl ester PA were detected as the major intermediates in the process of DMP degradation. Finally, DMP and all products were mineralized into carbon dioxide(CO_2) and water(H_2O) ultimately. Based on these analysis results, the degradation pathway of DMP by strong ionization discharge technology were proposed.     

月球及深空中子(水冰)探测进展

概述了人类对行星中子测量的研究现状,特别提及了月球中子探测的优势条件;阐明了利用中子测量技术进行行星表面水冰探测的基本原理;综述了几个近代月球及深空中子(水冰)探测的重大成功及获得的重要结论;最后在总结国内外研究现状的基础上指出开展该领域研究的急迫性及重大意义.     

Experimental Studies on Characteristics of Pressure Attenuation and Recovery to Saturation for Decompressive Disturbances in Low Pressurized Water

Slightly pressurized water (P _sat = 1.2–6.0 bar) was flashed into steam void by step decompression to atmospheric pressure, using a shock tube type device with vertical test section, made of stainless steel pipe about 2 m long, with an inner diameter of 40 mm. The transient pressure depression below saturation and the time constant of pressure recovery to the saturation were measured, based on the observed transient pressure response signals. The transient pressure curve could be approximated by the expression P(t) = P _min +(P _sat ?P _min )(1?e ^?t/τ) for the period immediately following step decompression. This time constant τ represents the effective relaxation time of thermodynamic nonequilibrium.

Defining the term decompression ratio ε as the ratio of the excess transient depression below saturation pressure to the difference between saturation and atmospheric pressure, i.e., ε=(P _sat ?P _min )/(P _sat ?P _fin ), the dependence of ε on the vertical position along the test column z and P _sat was found to follow approximately the empirical formula ε=exp[?β′{(P _sat /P _fin )?1}(z+z ⁰ )], where β was evaluated to be 0.43m^?1. Correspondingly, the attenuation constant β=(?1/ε)·dε/dz=β′{(P _sat /P _fin )?1}. The time constant τ was found to range between 10–300 msec, with a tendency to increase with decreasing saturation pressure determined by the measured water temperature. The value of τ showed little dependence on the position of observation along the test section. The expression 1/τ=βV (V being the propagation velocity of pressure waves) indicates a hyperbolic relation between τ and P _sat . This relation roughly agreed with experimental data.     

Hydrogen and Hydrazine Co-injection to Mitigate Stress Corrosion Cracking of Structural Materials in Boiling Water Reactors, (VI) The Effect of Ammonia on Intergranular Stress Corrosion Cracking

Hydrogen and hydrazine co-injection into a boiling water reactor was considered as a new mitigation method of stress corrosion cracking (SCC). In this method, some amount of ammonia will be formed by the decomposition of hydrazine. The effect of ammonia on SCC susceptibility was studied over a wide range of electrochemical corrosion potentials (ECPs) in 288_C water by conducting slow strain rate technique SCC experiments (SSRTs). ECP was changed from _0:6V versus the standard hydrogen electrode (V(SHE)) to 0.1 V(SHE) by controlling dissolved oxygen concentration. Ammonia concentration was controlled to have values of 100 and 530 ppb. Similarly, sulfuric acid was injected to confirm the difference in the effect of injected chemical compounds on SCC susceptibility. The intergranular stress corrosion cracking (IGSCC) fraction, which was used as the index of SCC susceptibility, decreased with decreasing ECP for the case of no chemical injection. Sulfuric acid enhanced the IGSCC fraction. These data were in good agreement with literature data. On the other hand, ammonia at less than 530 ppb did not affect IGSCC fraction. It is expected that 51–280 ppb hydrazine and 0–53 ppb hydrogen will be injected into reactor water to mitigate SCC in BWRs. In the bottom region of the reactor pressure vessel, ECP and ammonia concentration will be _0:1 V(SHE) and 15–60 ppb, respectively. Under these conditions, ammonia did not affect SCC susceptibility. So SCC susceptibility will be mitigated by decreasing the ECP using hydrazine and hydrogen co-injection.     

Experimental study of the residual activity induced by 950 MeV/u uranium ions in stainless steel and copper

As a preparatory work for constructing the FAIR facility at GSI, samples of stainless steel and copper were irradiated by 950 MeV/u ²³⁸U ions and depth-profiles of residual activity were measured by gamma-ray spectroscopy. The isotopes with dominating contribution to the residual activity were identified and their contributions were quantified. In contrast to the previous study performed at lower energies, the activities could no longer be determined from the full-assembly target measurements. Depth-profiling of residual activity of all identified isotopes had to be completed by measurements of individual target foils. The activity contributions were then obtained by integration of the depth-profiles.     

Preliminary Studies on Base Substitutions and Repair of DNA Mismatch Damage Stimulated by Low Energy N＋ Ion Beam Implantation in Escherichia coli

Ever since the low energy N+ ion beam has been accepted that the mutation effects of ionizing radiation are attributed mainly to direct or indirect damage to DNA. Evidences based on naked DNA irradiation in support of a mutation spectrum appears to be consistent, but direct proof of such results in vivo are limited. Using mutS, dam and/or dcm defective Eschericha coli imitator strains, an preliminary experimental system on induction of in vivo mutation spectra of low energy N+ ion beam has been established in this study. It was observed that the mutation rates of rifampicin resistance induced by N+ implantation were quite high, ranging from 9.2×10-8 to 4.9 ×10~5 at the dosage of 5.2 ×1014 ions/cm2. Strains all had more than 90-fold higher mutation rate than its spontaneous mutation rate determined by this method. It reveals that base substitutions involve in induction of mutation of low energy nitrogen ion beam implantation. The mutation rates of mutator strains were nearly 500-fold (GM2929), 400-fol