三种泡沫材料的吸放水性及微观结构

采用重量法和扫描电镜研究了硬质聚氨酯泡沫塑料、硅橡胶泡沫、半硬质自结皮聚氨酯泡沫的吸、放湿水性能和微观结构,比较分析和探讨了3种泡沫材料的吸、放水性及其机理,并提出减少泡沫材料中水份的有效途径。研究结果表明:3种泡沫材料的吸、放水性不同,即硬质聚氨酯泡沫塑料<硅橡胶泡沫<<半硬质自结皮聚氨酯泡沫,其吸、放水机理是由于开孔所致,如果密度越小且泡孔开孔率越高,则吸、放水能力越强。减少泡沫材料中水份的有效途径:(1)提高材料密度和闭孔率;(2)在材料表面镀金属膜或保留表皮;(3)进行适当干燥处理,并尽可能降低存放环境湿度。

三种有机泡沫材料的吸放水性及微观结构研究

采用重量法和扫描电镜研究了硬质聚氨酯泡沫塑料、硅橡胶泡沫材料、半硬质自结皮聚氨酯泡沫塑料的吸、放水性能和微观结构,比较了这三种泡沫材料的吸、放水性能及其机理。结果表明,这三种有机泡沫材料的吸、放水能力不同,硬质聚氨酯泡沫塑料的吸、放水能力<硅橡胶泡沫材料<半硬质自结皮聚氨酯泡沫塑料,其吸、放水机理与泡沫开孔有关,密度越小且泡孔开孔率越高,吸、放水能力越强。

蜜胺泡绵的吸放水性研究与应用

介绍了蜜胺泡绵的产品性能,并通过重量法研究了聚氨酯泡沫和不同密度的蜜胺泡绵的吸放水性能;比较分析了两种泡沫的吸放水机理,提出改善蜜胺泡绵吸放水性能的方法;并根据蜜胺泡绵优异的吸放水性能,提出其在种植基材、固沙保水和成人尿不湿等领域的应用前景,同时也为这些领域材料的选择提供了新的思路。

侏罗系煤田宝塔山砂岩含水层疏放水可行性研究

为了论证侏罗系煤田底板宝塔山裂隙砂岩含水层疏放可行性,选取宁东碎石井矿区灵新煤矿为例,利用井下单孔和多孔放水试验,分析了底板放水钻孔涌水量动态变化规律,评价了底板含水层放水效果和疏放可行性。结果表明:放水孔初期涌水量较大,经一周左右时间流量明显逐渐降低并趋于稳定;放水稳定时刻,形成以放水孔为中心的降落漏斗,且影响半径较大(均大于700m),各孔水压明显降低;由单孔放水到三孔叠加放水,降落漏斗形态不断扩大,影响半径逐渐增大,各孔水压逐渐降低。单孔放水阶段,FS2、G1和G2孔水压计算的底板突水系数小于正常标准(0. 1MPa/m);多孔放水阶段,FS2、JG、JF、G1和G2孔水压计算的底板突水系数小于正常标准。说明煤层底板砂岩含水层具有可疏放性,可通过底板钻孔放水实现对含水层的超前疏放,保障工作面的安全开采。

Microstructures and electrochemical corrosion properties of Mg-Al-Pb and Mg-Al-Pb-Ce anode materials

Mg-Al-Pb alloy is a good candidate for the anode material of magnesium seawater battery. For improving the low current utilization efficiency of Mg-Al-Pb alloy, the influence of Ce on the microstructures and electrochemical corrosion properties in a 3.5% NaCl solution was investigated using scanning electron microscope and electrochemical measurements. The results indicate that Ce refines the grain structure of Mg-Al-Pb alloy. The formation of strip Al11Ce3 second phase promotes the uniform distribution of Mg17Al12 phase in Mg-Al-Pb-Ce alloy. The addition of cerium accelerates the discharge activity of Mg-Al-Pb alloy. Due to a large number of cathodic Al11Ce3 and MglyAla2 phases, Ce promotes the micro-galvanic corrosion and leads to larger corrosion current density and hydrogen evolution rate in Mg-Al-Pb-Ce alloy than those in Mg-Al-Pb alloy. However, Mg-Al-Pb alloy expresses smaller utilization efficiency than Mg-Al-Pb-Ce alloy because of grain detachment.

pH Stability of Defibrase_ in Aqueous Solution Determined by En-zyme-linked Immunosorbent Assay

Stability of Defibrase in various pH buffer solutions was investigated. Enzyme-linked immuno-sorbent assay (ELISA) and coagulating time method were used to assess antigenic stability and coagulating stability, respectively. The change of antigenic activities and coagulating activities of Defibrase in the same buffer solutions (pH 6, 7 and 8, with the exception of pH 3.6) showed similar tendency to decline with the time. Concentrated Defi-brase was relatively stable at neutral pH 6~7, more than 95% of its initial activities (100BUmL-1) was kept after a 10-day storage at 40 oC, whereas in pH 3.6 and pH 9 buffer solutions, diluted Defibrase was very labile. Addition of Triton X-100 or bovine serum albumin could effectively prevent loss of Defibrase by minimizing adsorption of De-fibrase to plastic surface (P<0.005). Concentration of Defibrase could also affect its stability in aqueous solutions.

Removal of strontium ions from aqueous solution using hybrid membranes: Kinetics and thermodynamics

The removal of radionuclide from radioactive wastewater has captured much attention.Strontium-90 is one of the major radionuclides.To develop a new type of adsorbents to remove strontium ions from the radioactive wastewater,in this study,novel hybrid membranes were prepared and characterized.The adsorption kinetics,thermodynamic parameters of AG,AH and AS,as well as surface SEM and EDS images were used to investigate the removal of strontium ions from stimulated radioactive wastewater using the previously prepared hybrid membranes as efficient adsorbents.The study of kinetic model confirmed that the adsorption of strontium ions on these hybrid membranes followed the Lagergren pseudo-second order model.Moreover,it was proved that the adsorption of strontium ions on these samples was solely controlled by intraparticle diffusion.The negative values of AG and the positive values of AH indicated that the adsorption of strontium ions on samples A-D is a spontaneous and endothermic process in nature.Furthermore,surface SEM and DES images give significant evidence to confirm the existence of strontium ions on the surface of the adsorbed samples.These findings demonstrate that these hybrid membranes are promising adsorbents for the removal of strontium ions from aqueous solution and can be potentially applied in the adsorptive separation of radionuclides from the radioactive wastewater.

Application of waterborne acrylic emulsions in coated controlled release fertilizer using reacted layer technology

Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release profiles of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate sodium could not improve water resistance performance and glass transition temperature Tgof coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and Tg. Incorporation of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated controlled release fertilizer, with the 30-day cumulative nutrient release reduced to 16% and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection.

Assessment of Present and Future Radioactive Contamination at Global Scale

As a result of more than two thousand nuclear tests performed since 1945, two war actions and few accidents in nuclear reactor, it does already exist a radioactive contamination at global scale. This contamination has been accumulated mainly in marine sediments, because sea is about 80% of planet surface, and solid fission products released by nuclear explosions are transported by wind first and then by rain to liquid and solid portions on earth, while gaseous fission products are diffused in the atmosphere. In this way, heavy, high yielding fission products, such as 137Cs, get marine sediments, where they are found mixed with heavy radioactive natural elements such as U, Th and their also radioactive decay products. But since alkaline are so abundant on earth, it is also found natural radioactive isotope 4~K, 0.0118% of isotopes forming K element, with half life 1.28 ~ l09, in the time range of planet age and elements origin. So, one easy way to assess both the importance and evaluation of radioactive contamination at global scale should be to establish a RCF （radioactive contamination factor） as a percentage of 137Cs contaminant radioactivity in marine sediments, compared to 4~K natural radioactivity present from the very beginning of earth, both expressed as Bq per gram of sediment. In the frame of these rather general considerations, a research project has started in Mexico whose varied purposes are： to characterize sea regions in both vast littorals in the country, by its natural 4~K radioactivity present in sea salts, as well as to determine if 137Cs traces produced by recent radioactive contamination have reached their coasts. Also, to assess the 137Cs traces already present in marine sediments as a result of more than two thousand nuclear test explosions performed till now, rather than contamination produced by four main accidents in nuclear reactors during the last 60 years. It is proposed a radioactive contamination factor obtained from samples taken up in both coasts during the last two years, which should be very useful in two ways： first to assess the real danger of radioactive contamination already present by comparing with natural radioactivity, and second to assess the growth, equilibrium or drop of radioactive contamination, given that nuclear energy is still the best option to solve the large energy demand foreseen in the near future.

A New Method for the Non-destructive Determination of Fish Freshness by Nuclear Imaging

A new method for determining the freshness of harvested carp using nuclear imaging technology is presented.This research attempted to determine the freshness of carp by measuring the radioactive area increase (RAI) value of fish.The carp samples were maintained under refrigerated condition for 12d, and RAI and total volatile base nitrogen (T-VBN)values were determined during the storage. The results showed that the RAI value increased with the T-VBN content duringthe storage. Also, there is a significant correlation between T-VBN content and RAI value of the carp kept in refrigeratedcondition. The results of this study suggest that the RAI value could be utilized to evaluate rapidly the freshness of carp.

Assessment of natural radioactivity levels in Yemen rocks

Studies on radiation level and radionuclide distribution in Yemen were studied. The samples were collected from eight locations： Ma＇rib, A1 Jawf, Sana＇a, Dhamar, Amran, Ibb, Al Bayda and Al Dalea. The purpose of this study is to provide a baseline map of radioactivity background levels in the investigated area and this study will be used as reference information to assess any change in the radioactive background level due to geological processes. The highest values of 22~ and 2~l＇h concentrations （8797.2 and 24984.1 Bq.kg＂l, respectively） were observed at A1 Jawf, region, whereas the highest average value of 40K concentration was 1561.9 Bq.kg-1. The investigation of the geological maps of the area under study showed that the surface rock outcrops consist mainly of granites, diorite, granodiorite, gneisses, and schists. All these rock types arc known to be rich in radioactive materials, which are considered natural sources for gamma radiation. The low mdiological background characterizing some Yemeni rocks could be attributed to nature of these rocks which consist of lime stone （sands and gravels）. The absorbed dose rate in air was found to be in the range between 5.40 and 45.11 nGy.h-1 depending on the geological features, and radium equivalent activity concentration was found in the range between 29.57 and 71.85 Bq.kg-1. Also the representative extcmal hazard index values for the corresponding samples were also estinlated and given.

Magnesium (II) Adsorption from Aqueous Solutions on China Clay and the Stability Constants for Complex Formation

China clay was employed as an adsorbent for the removal of Mg 2+ from water at pH 7.0 within the temperature range of 303～328 K. The linearity of the plots indicated Langmuir type isotherms. The reaction was exothermic. A maximum removal of 35% was obtained at 0.50 mmol L -1 metal concentration and a pH of 7.0 at 303 K. The H + rel /Mg 2+ ads ratio changed from a fractional value to 2.5. Strong chemical bondings took place between oxygen atom of the surface and Mg 2+ , resulting in a surface complex species. Temperature had a significant effect on H + rel , and the stability constants also increased with increasing temperature.

Coupled thermo-hydro-mechanical-migratory model for dual-porosity medium and numerical analysis

A coupled thermo-hydro-mechanical-migratory model of dual-porosity medium for saturated-unsaturated ubiquitous-joint rockmass was established,in which the stress field and the temperature field were single,but the seepage field and the concentration field were double,and the influences of sets,spaces,angles,continuity ratios,stiffnesses of fractures on the constitutive relationship of the medium were considered.Also,the relative two-dimensional program of finite element method was developed.Taking a hypothetical nuclear waste repository as a calculation example,the case in which the rockmass was unsaturated dual-porosity medium and radioactive nuclide leak was simulated numerically,and the temperatures,negative pore pressures,saturations,flow velocities,nuclide concentrations and principal stresses in the rockmass were investigated.The results show that the negative pore pressures and nuclide concentrations in the porosity and fracture present different changes and distributions.Even though the saturation degree in porosity is only about 1/10 that in fracture,the flow velocity of underground water in fracture is about three times that in porosity because the permeability coefficient of fracture is almost four orders higher than that of porosity.The value of nuclide concentration in fracture is close to that in porosity.

RADIOACTIVE OR NATURAL TRACER TECHNIQUES FOR LEAK DETERMINING OF DAM ABUTMENT

Infiltration and localization of preferential infiltration zones at the dam abutment are measured using radioactive tracer tests of flow in boreholes, meanwhile interconnection between boreholes and the energing water points is analysed. The theory and practice of radioactive tracer synthetic detective method are described to give methods and calculation formulae used under the condition of stable flow in single well to measure permeability coefficient and hydrostatic heads. Major single hole techniques including measurement for seepage line, velocity, rate of seepage flow and relationship of recharge of groundwater in aquifers are introduced briefly.The possibilities offered by natural tracers are analysed, including electric-conduct,pH-value and temperature of water as well as stable isotopes (D, 18O) and tritium.Furthermore, the sensibilities of this theory and methods were confirmed by detecting seepage flow field of Xinanjiang Dam.

Chemical Contamination and Radiological Risk Assessment of Water Sources in Richards Bay

South Africa is pronounced a dry country. Though KwaZulu-Natal has a higher rain fall than most part of the country, it has recorded cases of austere droughts. The present study was aimed at examining the quality of water within Richards Bay precinct in relation to South African target water quality range （TWQR）. Fifty water samples were collected from five water sources （effluent, stream, Mzingazi River, Indian Ocean and Esikawini drinking tap water） and analyzed using ICP-MS technique to determine the concentrations of some traced metals i.e., Fe, Cu, T1, Zn, Pb, Cr, and Ni. The main impurities were found to be Cd, Mn and As with concentrations of 2.21 × 10^0mg. l-1, 7.19 × 10-1mg.l-1and 2.72 ×10-3mg. 1-1 respectively. The surface gross alpha contamination of mineral stores within the facilities ranges from 1.00 × 10-4 ± 1.5 × 10-2 Bq.cm-2 to 1.45× 10-2 ±4.20 ×10-3Bq.cm-2 with a mean concentration of 1.15 × 10-2 ±1.36 ×10-2Bq.cm-2while the gross beta contamination ranges from 1.00 ×10-3 ± 1.14 × 10-ZBq, cm-2 to 4.15 × 10-2 ± 2.17 × 10-2Bq. cm-2 with a mean concentration of 2.15 ×10-2 ±1.80×10-2Bq. cm-2. The result indicated that the water quality was acceptable.

Recurrent ascites due to spontaneous intraperitoneal bladder rupture after pelvic radiation therapy for cervical cancer

Radiation cystitis is one of the major complications following radiotherapy for cervical cancer. However, spontaneous intraperitoneal bladder rupture as a result of radiation cystitis following radiotherapy for cervical cancer is extremely rare. Case presentation: We report a 52-year-old patient who received radiation therapy for cervical cancer 15 years prior to presentation. Eight years prior to presentation, she developed recurrent abdominal distension, oliguria, and ascites. Following ascites drainage and supportive treatment, all symptoms were relieved. However, all symptoms subsequently recurred every few months. The patient underwent exploratory laparotomy twice. The first exploratory laparotomy in July 2015 found no specific abnormalities. The second exploratory laparotomy in November 2016 found an intraperitoneal bladder rupture, and the patient underwent surgical repair. The ascites subsequently resolved. Conclusion: The occurrence of spontaneous intraperitoneal bladder rupture after radiation therapy for cervical cancer is rare. The prognosis is good when diagnosis and treatment are prompt.

Radiation-Chemical Situation of the Waters of the Middle Reach of the River Yenisei （Russian Federation）

The results of monitoring the radiation-chemical situation in the middle reach of the Yenisei River located in the nearest zone of the influence of the Mining and Chemical Combine of Rosatom have been described in the paper. Using different physico-chemical methods, it has been found that uranium and tritium content in the water exceeds the background values of the flood plain of the River Yenisei. It has been shown that a wide range of radionuclides of different genesis flows into the waters of the Yenisei River. It has been demonstrated that radionuclides are transported by the water flow in the form of molecular solution or with suspended matter. In this case, the suspended matter consists of pelitic finely dispersed mineral particles, plant and organic detritus and living biological objects （for example, worms）. It has been shown that the main contribution to radionuclide and metal accumulation is made by humic substances covering the panicles of the suspended matter and actively participating in the formation of complexes with radionuclides and heavy metals. As a result of this work, the artificial radionuclide inflow into the ecosystem of the River Yenisei has been evidenced.

Sensitivity of Climate Changes to CO_2 Emissions in China

In this study, the authors demonstrate that the Coupled Model Intercomparison Project Phase 5 （CMIP5） models project a robust response in changes of mean and climate extremes to warming in China. Under a scenario of a 1% CO2 increase per year, surface temperature in China is projected to increase more rapidly than the global average, and the model ensemble projects more precipitation （2.2%/℃）. Responses in changes of climate extremes are generally much stronger than that of climate means. The majority of models project a consistent re- sponse, with more warm events but fewer cold events in China due to CO2 warming. For example, the ensemble mean indicates a high positive sensitivity for increasing summer days （12.4%/℃） and tropical nights （26.0%/℃）, but a negative sensitivity for decreasing frost days （-4.7%/℃） and ice days （-7.0%/℃）. Further analyses indicate that precipitation in China is likely to become more extreme, featuring a high positive sensitivity. The sensitivity is high （2.4%/℃） for heavy precipitation days （〉 10 mm d l） and increases dramatically （5.3%/℃） for very heavy precipitation days （〉 20 mm d-1）, as well as for precipitation amounts on very wet days （10.8%/℃） and extremely wet days （22.0%/℃）. Thus, it is concluded that the more extreme precipitation events generally show higher sensitivity to CO2 warming. Additionally, southern China is projected to experience an increased risk of drought and flood occurrence, while an increased risk of flood but a decreased risk of drought is likely in other regions of China.

Upgrade to Nuclear Power Plant Krsko Internal Flooding Probabilistic Safety Analysis

The original internal flooding probabilistic safety analysis （PSA） study of Krsko Nuclear Power Plant （two-loop Pressurized Water Reactor （PWR） plant of Westinghouse design） was performed in mid nineties and limited to reactor core damage risk （Level 1 PSA）. In 2003, it was, together with other safety and hazard analyses, subject to the Periodic Safety Review （PSR）. In the PSR, it was stated that methodological PSA approaches and guidelines have evoluted during the past decade and several observations were provided, concerning the area screening process, residual risk and treatment of plant damage states and risk from radioactivity releases （i.e., Level 2 PSA）. In order to address the PSR observations, upgrade ofKrsko NPP internal flooding PSA was undertaken. The area screening process was revisited in order to cover the areas without automatic reactor trip equipment. The model was extended to Level 2. Residual risk was estimated at both Level 1 and Level 2, in terms of core damage frequency （CDF） and large early release frequency （LERF）, respectively.

Study of the Positioning Influence in the Water Activity Measurement during Leak Test of Iodine-125 Seeds

In the prostate cancer treatment, brachytherapy with iodine-125 seeds has been used. lodine-125 seeds are sealed radioactive sources, made by a titanium capsule containing the radioisotope inside. In the final phase of the seeds production, it is necessary to ensure that there is no leakage of the radioactive material. A leakage test is performed, immersing the seeds in water during 24 h and measuring the resulting activity in the water. This measurement is made in a sodium iodide detector. The immersion water is transferred to a plastic tube with a cap. The tube is placed by an automated positioning system, in the detector chamber. This study aims to determine the best positioning of the tube for the detection. It is also important to determine the influence of the positioning variation intrinsic of the automated positioning system during the iodine-125 seeds production. The results obtained will be used as a reference to adjust the equipment and process control system, in the production of the iodine-125 seeds.