Effect of drying cracks on swelling and self-healing of bentonite-sand blocks used as engineered barriers for radioactive waste disposal

Experiments were conducted to evaluate the healing of drying cracks in air-dried bentonite-sand blocks after hydration and swelling in groundwater,providing justifications to simplify the protection of blocks prior to installation in a high-level radioactive waste repository.Synthetic groundwater was prepared to represent the geochemistry of Beishan groundwater,and was used to hydrate the blocks during the swelling pressure and swelling strain measurements,as Beishan is the most promising site for China's repository.Healing of the surface cracks was recorded by photography,and healing of the internal cracks was visualized by CT images and hydraulic conductivity of air-dried blocks.The results indicate that the maximum swelling pressure and swelling strain are primarily affected by the geochemistry of Beishan groundwater,but not affected by the drying cracks.The maximum swelling pressure and swelling strain of air-dried blocks are comparable to or even higher than the pressure and strain of fresh blocks.The maximum swelling pressure measured in strong(i.e.high ion strength)Beishan groundwater was 44%of the pressure measured in deionized(DI)water,and the maximum swelling strain was reduced to 23%of the strain measured in DI water.Nevertheless,the remained swelling of the blocks hydrated in strong Beishan groundwater was sufficient to heal the surface and internal drying cracks,as demonstrated by the pictures of surface cracks and CT images.The hydraulic conductivity of the air-dried block permeated with strong groundwater was comparable(3.7×higher)to the hydraulic conductivity of the fresh block,indicating the self-healing of drying cracks after hydration and swelling in groundwater.A simplified method of protecting the block with plastic wraps before installation is recommended,since the remained swelling of the block hydrated in Beishan groundwater is sufficient to heal the drying cracks.

DC ARC发射光谱法测定纯金中18个杂质元素

用DCARC发射光谱法研究了纯金中杂质元素的定量分析方法,配制了一套适合贸易、科研、生产的光谱标样。本方法可以一次定量测定纯金中18个杂质元素,还进行了检出限和测量不确定度实验,结果表明方法的检出限较低,不确定度低,各杂质元素的相对标准偏差一般<10%,检测方法具有准确度高,检测速度快,效率高的特点。

Causes of color changes in wood during drying

The forest industry operates in a dynamic and global market where change and competition are the rule rather than the exception. The color of wood is one of the most attractive features for the modem wood industry. Even when wood is chosen for its structural qualities, attractive and decorative colors are usually an important factor. In many applications, particularly in furniture, decorative products, decorative veneers and flooring, accurate matching of the color of different samples is required. Wood attributes and properties are important because they have a direct bearing on market opportunities and consumer acceptance for many types of manufactured wood products. The aim of this review is to identify causes of wood discoloration and advances in drying technology to overcome this problem. Wood discoloration is a complex phenomenon, mainly affected by heat, light, physiological and biochemical reactions, as well as from attack by microorganisms.

Quantitative behavior of vibrational excitation in AC plasma assisted dry reforming of methane

Quantitative behavior of non-equilibrium excitation by direct electron impact in low-temperature dry reforming of methane was investigated by integrated studies of experimental validation and kinetic modeling.A plasma chemistry kinetic mechanism incorporating the reactions involving vibrational excitation of CH4,CO2,H2 and CO molecules as well as the low temperature He/CH4/CO2 conversion pathways was developed and validated.The calculation results showed that at lower E/N values(<150 Td)large population of energized electrons generated in a He/CH4/CO2 discharge resulted in an intensification of vibrational excitation.Despite the large generation of vibration,the vibrationally excited molecules in a 0.5/0.25/0.25 of He/CH4/CO2 discharge mixture were easy to relax,due to the strong coupling of the vibration of different molecules in a gas mixture.The results showed that the moderate levels of the vibrational excitation,such as CO2(v10,11,...,18)and CO(v9,10),presented most efficient in the stimulation of species generation including CO,CH2 O,CH3 OH,C2 H4 and C2 H6.Specifically,under conditions of E/N of 108 Td,14.9%of CO formation was estimated from the recombination of CO2(v)with CH3 and H,CO2(v)+CH3→CH3 O+CO,CO2(v)+H→CO+OH.Also,4.8%of C2 H4 formation was from the recombination reaction CH4(v)+CH→C2 H4+H.These results highlight the strong roles of vibrational states in a complex plasma chemistry system.

Synthesis and Characterization of Y_ (0.9-x)Gd_xEu_(0.1)BO_3 Phosphors by Spray Drying Process

Y 0.9-xGd xEu 0.1BO 3 phosphors were synthesized by spray drying (SD) method, and the results were compared with those by conventional solid state (SS) and citrate gel (CG) methods. The PL intensity of phosphors increases with the increase of x value in Y 0.9-xGd xEu 0.1BO 3 (prepared by SD) due to an energy migration process like Gd 3+-(Gd 3+) n-Eu 3+ occurred in the material. Compared with the latter two methods, the phosphor particles prepared by spray drying method have a better morphology, such as homogeneous size (about 1～3 μm) with spherical shape and smooth surface. Furthermore, the spray drying-derived phosphors have higher photoluminescence (PL) intensity than those by citrate gel method, but still a little lower than those by the solid state method.

Chlorine drying with hygroscopic ionic liquids

The chlorine(Cl2)drying technology using ionic liquids(ILs)as absorbents was proposed for the first time and systematically investigated from the molecular level scaled up to the industrial level.The hygroscopic IL[EMIM][CH3SO3]was screened as a suitable absorbent from 238 potential IL candidates consisting of 14 cations and 17 anions,by calculating the Cl2 and H2O solubility and separation selectivity of Cl2 to H2O in different ILs based on the COSMO-RS model.The microscopic atomic and molecular insights into the separation mechanisms were deeply revealed by using COSMO-RS model analyses(i.e.,σ-profiles,σ-potentials,excess enthalpies,entropies,and Gibbs free energies)and quantum chemistry calculation(binding energies and weak interaction analyses).The Cl2 solubility in pure IL and H2O+IL systems were predicted by the COSMO-RS model,and the results agree with the microscopic mechanism identification.Moreover,the strict equilibrium stage model employed with the COSMO-RS model parameters was built to perform the process simulation,and continuous Cl2 drying with ILs was conceptually designed and optimized at industrial scale.It was confirmed that[EMIM][CH3SO3]is a very promising absorbent leading to a less IL amount,a much lower energy consumption than the other IL[EMIM][BF4],which has a very bright industrialization potential used for Cl2 drying technology.

Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges

The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor （ACDR） powered by a DC high voltage supply. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The study compares the results obtained in dry air and in air mixed with a small amount of water vapour （humid air）. The simulation involves the electro-dynamics~ chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation. Each discharge lasts about one hundred of a nanosecond while the post- discharge occurring between two successive discharges lasts one hundred of a microsecond. The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO. After 5 ms, the time corresponding to the occurrence of 50 successive discharge/post-discharge phases, a higher NO removal rate and a lower ozone production rate are found in humid air. This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.

染料在干污泥上的吸附平衡和动力学

本文研究了染料活性嫩黄 KD- 3G、直接深棕 M和酸性媒介棕 RH在干活性污泥上的吸附平衡和吸附动力学。结果表明 :所试染料的吸附等温线数据都可用 Freundlich方程描述 ;对于 Langmuir方程 ,只有酸性媒介深棕 RH的等温线数据能与之拟合。染料的吸附过程遵循二级吸附动力学模型 ,也能用 Lagergren一级速率方程描述。在吸附温度为 1 5℃、2 0℃、2 5℃、35℃和 45℃时 ,活性嫩黄 KD-3G、直接深棕 M和酸性媒介棕 RH的一级吸附速率常数分别为 0 .0 0 2 8～ 0 .0 0 3 2 min- 1、0 .0 1 5～ 0 .0 4 0 min- 1、0 .0 0 7～ 0 .0 1 2 min- 1 ,二级吸附速率常数分别为 0 .0 0 0 2 7～ 0 .0 0 0 4 7g/ (mg· min)、0 .0 0 6 5～ 0 .0 2 90 g/ (mg· min)、0 .0 0 3 0～ 0 .0 1 3 2 g/ (mg· min)。由二级吸附速率方程计算得到的平衡吸附量与实验值的相对误差在 1 0 %以内 ,这表明两者的符合程度较高。上述温度范围内 ,当染料质量浓度为50 mg/ L时 ,活性嫩黄 KD- 3G、直接深棕 M和酸性媒介棕 RH的平衡吸附量分别为 1 6.5～ 1 9.2 mg/ g、1 4 .3～ 1 6.0 mg/ g、7.2～ 9.6 mg/g。

中药野马追的研究进展

菊科植物野马追主产于江苏省盱眙县,具有化痰、止咳、平喘的功效,用于治疗慢性气管炎、支气管炎等呼吸系统疾病。本综述通过系统地查阅关于野马追的国内外相关文献,对野马追药材的分布与利用、药材质量标准、化学成分、药理作用与临床应用等方面的研究进行了阐述,希望能够让科研工作者全面而系统地认识野马追,并为其进一步深入的研究提供参考。

物理化学在药剂学领域的应用

从物理化学在药剂学领域包括药物新剂型设计、药用辅料选择和制剂干燥成型技术3个方面的应用情况，着重介绍物理化学的基础知识和基本理论在药剂学领域的指导作用，以期加强物理化学教学内容与药剂学专业知识的融合，激发药剂学专业大学生学习物理化学的兴趣和提高课堂教学质量。

苦马豆果皮中紫檀烷和异黄酮类化合物的分离与鉴定

目的分离、鉴定苦马豆 (SphaerophysasalsulaDC )果皮乙醇提取物中的化学成分。 方法利用硅胶柱色谱、制备薄层色谱进行分离纯化 ,根据理化性质和光谱数据进行结构鉴定。结果得到 4个化合物 ,分别鉴定为 :大豆素二甲醚 (4′,7 二甲氧基异黄酮 ,Ⅰ )、(-) 紫檀素 [(-) (6aR ,1 1aR) 3 甲氧基 8,9 亚甲二氧基紫檀烷 ,Ⅱ ]、(-) 1 0 甲氧基美迪紫檀素 [(-) (6aR ,1 1aR) 3 羟基 9,1 0 二甲氧基紫檀烷 ,Ⅲ ]、毛蕊异黄酮 (3′,7 二羟基 4′ 甲氧基异黄酮 ,Ⅳ )。化合物Ⅱ、Ⅲ为首次从该属植物中分得。

野艾蒿的化学成分研究

【目的】研究野艾蒿的化学成分。【方法】采用反复硅胶、葡聚糖凝胶色谱方法进行分离、纯化野艾蒿的化学成分,通过理化性质和波谱技术对化合物进行结构鉴定。【结果】从野艾蒿中分离得到12个化合物,其结构鉴定分别为7-甲氧基香豆素(1),间羟基苯甲酸(2),异阿魏酸(3),黑麦草内酯(4),medioresinol(5),(+)-丁香树脂醇(6),丁香酸(7),木栓醇(8),咖啡酸(9),香草酸(10),豆甾醇(11),胡萝卜苷(12)。【结论】化合物1～12均为首次从该植物中分离得到。

高效液相色谱法测定两面针不同药用部位氯化两面针碱的含量

【目的】比较广东、广西产两面针不同部位中氯化两面针碱的含量差异。【方法】采用体积分数70%甲醇超声提取,高效液相色谱法(HPLC)测定,色谱柱为Hypersil ODS C18(4.6mm×200mm,5μm);以乙腈为流动相A,1.22g/L甲酸—三乙胺(pH4.5)为流动相B,梯度洗脱。【结果】氯化两面针碱的平均回收率和sR分别为98.32%、1.85%。广西、广东产两面针根中均含有氯化两面针碱,且含量最高;广西产两面针茎中含氯化两面针碱,而广东产茎中含或不含氯化两面针碱,其含量低于广西产,两产地叶中均不含氯化两面针碱。【结论】不同来源和不同部位两面针中氯化两面针碱含量存在一定的差异,该测定方法简单、快速、准确可靠,可为两面针药用部位的选取和资源合理开发利用提供参考。

瘤果槲寄生化学成分的研究

[目的]研究槲寄生属植物的化学成分。[方法]应用柱层析和结晶方法进行分离、纯化,并采用光谱学方法进行结 构鉴定。[结果]分离并鉴定出3个化合物:羽扇豆醇乙酸酯(lupeol acetate)(Ⅰ)、β-香树脂醇(β-amyrin)(Ⅱ)、齐墩果 酸(oleanolic acid)(Ⅲ)。[结论]3个化合物均为首次从瘤果槲寄生中分离得到。

地高辛的体内分析方法应用与进展

目的总结地高辛血药质量浓度监测方法,寻求最适的测定方法。方法对近年来国内外与地高辛监测相关的文献进行检索综述分析。结果地高辛血药浓度测定方法很多,常用方法主要有:FPIA、酶免疫分析法、RIA、CLIA、乳胶免疫抑制法、干化学法、HPLC法等。结论通过比较分析其中RIA、CLIA、EIA和HPLC MS 4种方法更好。

纵向磁场对直流真空电弧等离子体发展进程的影响研究

从微观角度出发,数值模拟直流真空电弧燃弧初期电弧的发展进程,研究纵向磁场对电弧等离子体参数输运特性的影响。建立电弧等离子体流体-化学混合模型,仿真研究纵向磁场作用下的电弧运动特性。数值模拟电弧等离子体中粒子输运特性,以得到电弧等离子体参数随磁场变化规律。仿真结果表明:纵向磁场分布对直流真空电弧放电初期粒子的数密度与温度等参数的作用,直接影响电弧的发生与发展。研究并分析了直流真空电弧燃弧初期的过程。

陕西省不同市区的北柴胡药材质量的分析

采用可见分光光度法和高效液相色谱法对产于陕西省不同市区的北柴胡药材中柴胡总皂苷及柴胡皂苷a的含量进行了测定。结果显示,陕西省不同市区北柴胡药材中的柴胡总皂苷和柴胡皂苷a的含量差异较大。其中汉中产北柴胡药材中柴胡总皂苷和柴胡皂苷a含量均最高,分别为2.898%和1.049%;而安康产北柴胡药材中两者含量均最低,分别为1.528%和0.231%。由此可见,由于药材的产地不同,药材的品质存在一定的差异。

利用直流电压法在线测试碳钢的流动加速腐蚀减薄速率

根据试样直流电压随厚度变化的规律,自主设计并搭建了一套能在高温高压水环境下在线测试碳钢流动加速腐蚀减薄速率的试验装置,并利用该装置在模拟压水堆核电厂二回路水化学工况下对A106GrB碳钢进行了长时间的流动加速腐蚀试验。结果表明:采用该方法在线测试管壁减薄速率是合理可行的,所得结果与挂片试验结果的吻合度高,可用于测试材料的流动加速腐蚀速率。

木棉花干花产品包装适性研究

[目的]探索适合于木棉花干花产品的包装方法。[方法]以聚乙烯薄膜和铝箔为材料,试验4种包装方法对木棉花干花产品品质的影响。[结果]铝箔配合聚乙烯薄膜的包装方法,在保持产品颜色,防止褐变、吸潮和菌落总数控制等方面,均表现出较好的效果。[结论]铝箔配合聚乙烯薄膜的包装方法适合于木棉花干花产品包装。

杨木BECMP浆湿部化学性能及其对AKD施胶效果的影响

以细小纤维含量、Zeta电位、保水值、羧基含量及溶解胶体物质(DCS)含量为主要指标,通过与APMP浆和HBKP浆(杨木硫酸盐漂白浆)对比研究了杨木BECMP浆(挤压法漂白化机浆)的湿部化学性能。结果表明,BECMP浆具有较高的细小纤维含量、阴离子基团含量及DCS含量等特性。通过AKD(烷基烯酮二聚体)施胶效果的研究表明:BECMP浆的施胶效果明显优于HBKP浆,轻度施胶效果比APMP浆差,但当AKD用量达到或超过0.2%时,其施胶效果优于APMP浆。此外,BECMP浆的细小纤维及DCS会对其AKD施胶产生负面影响,但影响强度低于APMP浆。