Relevance of air conditioning for 222Radon concentration in shops of the Savona Province, Italy

Radon (222Rn) concentration was evaluated in shops of the Savona Province, Italy, between summer 2002 and winter 2002-2003. The main characteristics of each shops were recorded through a questionnaire investigating the ventilation rate and factors related to 222Rn precursors in the soil and the construction materials. The main variables that were related to radon concentration were the following: age of the building, level of the shop above ground, season of the year, wind exposure, active windows, and type of heating system. Shops equipped with individual air heating/conditioning systems exhibited radon concentrations that were three times higher than those of shops heated by centralized furnaces. Our data indicate that the level of pollution in the shops was of medium level, with an expected low impact on the salespersons' health. Only in wintertime, the action level of 200 Bq m(-3) for the confined environment was reached in 10 shops equipped with individual air heating/conditioning systems.     

Sources and temporal dynamics of arsenic in a New Jersey watershed, USA

We examined potential sources and the temporal dynamics of arsenic (As) in the slightly alkaline waters of the Wallkill River, northwestern New Jersey, where violations of water-quality standards have occurred. The study design included synoptic sampling of stream water and bed sediments in tributaries and the mainstem, hyporheic-zone/ground water on the mainstem, and seasonal and diurnal sampling of water at selected mainstem sites. The river valley is bordered by gneiss and granite highlands and shale lowlands and underlain by glacial deposits over faulted dolomites and the Franklin Marble. Ore bodies in the Marble, which have been mined for rare Zn ore minerals, also contain As minerals. Tributaries, which drain predominantly forested and agricultural land, contributed relatively little As to the river. The highest concentrations of As (up to 34 mug/L) emanated from the outlet of man-made Lake Mohawk at the river's headwaters; these inputs varied substantially with season--high during warm months, low during cold months, apparently because of biological activity in the lake. Dissolved As concentrations were lower (3.3 microg/L) in river water than those in ground water discharging into the riverbed (22 microg/L) near the now-closed Franklin Mine. High total As concentrations (100-190 mg/kg) on the <0.63 microm fraction of bed sediments near the mine apparently result from sorption of the As in the ground-water discharge as well as from the As minerals in the streambed. As concentrations in river water were diluted during high stream flow in fall, winter and spring, and concentrated during low flow in summer. In unfiltered samples from a wetlands site, diurnal cycles in trace-element concentrations occurred; As concentrations appeared to peak during late afternoon as pH increased, but Fe, Mn, and Zn concentrations peaked shortly after midnight. The temporal variability of As and its presence at elevated concentrations in ground water and sediments as well as streamwater demonstrate the importance of (1) sampling a variety of media and (2) determining the time scales of As variability to fully characterize its passage through a river system.     

从培养学生创新能力入手加强化学院食品微生物学实验教学改革

从实验教学方法、教学手段、教学内容,教材体系、教学管理,考试制度等方面着手,深入开展化学院食品微生物学实验教学改革,开展了有层次的实验教学,开设了综合性设计性实验、开放了实验室、开辟了学生课外科研活动,基本构建新型实验教学体系,为培养创新型、技术型人才打下坚实基础,并取得了良好的教学效果。     

关于化工工艺学教学改革的探讨

本文从强化课堂教学、加强实践与理论教学相结合以及强化学生工程观念等方面对《化工工艺学》课程教学方法的改革进行了探讨,提高了教学质量和教学效果,为更好地培养具有较强综合能力的化工工艺专业合格人才提供了重要保证。     

琥珀酸酯磺酸盐表面活性剂的合成和性能研究

从顺丁烯二酸酐衍生物表面活性剂出发,合成了琥珀酸酯磺酸盐这一类型具有多个亲水、亲油基团的新型表面活性剂;分别对合成的几个系列的多种醇类对应酯的琥珀酸酯磺酸盐表面活性剂在起泡、表面张力等方面的性能进行了测试和分析。     

基于Midplane网格单元HyPermesh与Moldflow的网格前处理

基于midplane网格类型,比较Hypermesh与Moldflow的网格前处理功能,从而说明使用Hypermesh作Moldflow的midplane网格的前处理,可大大提高网格划分速度和网格质量,为Moldflow的实际工程应用提供一种新的网格划分思路。     

陶艺的思维和创作-论陶艺创作的逻辑思辩

从陶瓷艺术的渊源及其发展变化的趋向,全面阐述了传统陶瓷艺术与现代陶艺的创作思维方法,并指出了现代陶艺家利用逻辑思辩的方法—反面思维法,进一步丰富和完善了陶艺创作的思维方式,拓宽了陶艺的创作思维空间。     

Role of bulky polysiloxanylalkyi methacrylates in oxygen-permeable hydrogel materials

Polysiloxanylalkyl methacrylates, such as methacryloxypropyl tris(trimethylsiloxy)silane (TRIS), have been used extensively in rigid gas-permeable contact lens materials due to their ability to produce high oxygen permeability in the resulting polymeric material. In this study, the role of TRIS was evaluated as a component in silicone hydrogel materials based on polysiloxane-based prepolymers. It was found that it not only gave high oxygen permeability, but also gave hydrogels with better tear strength and lower modulus. These changes in properties are all favorable for applications such as oxygen-permeable hydrogel lenses. © 1995 John Wiley & Sons, Inc.     

Effect of Structural Parameters on the Thermal Stress of a NiFe2O4-Based Cermet Inert Anode in Aluminum Electrolysis

Inert anode has been a hot issue in the aluminum industry for many decades. With the help of FEA(finite element analysis) software ANSYS,a model was developed to simulate the thermal stress distribution working condition of an inert anode. To reduce its thermal stress,the effect of some parameters on the thermal stress distribution was investigated,including the anode height,the anode radius,the hole depth,the hole radius,and the radius of inner chamfer and outer chamfer. The results showed that in the actual working condition of an inert anode,there existed a large axial tensile stress near the tangent interface between the anode and bath,which was the major cause of anode breaking. Increasing the anode height and reducing the hole depth properly seemed to be beneficial for the stress distribution. With the increase of anode radius,the stress distribution became better first and then deteriorated,the reasonable value was between 0.045 to 0.06m. The hole radius had a significant effect on the stress and a smaller radius would reduce the thermal stress. The effect of the radius of the inner chamfer and the outer chamfer was less than other parameters.     

催化裂化装置中大型波纹管膨胀节失效分析

对某石化公司催化裂化装置中泄漏的大型波纹管膨胀节进行了失效分析.结果表明,应力腐蚀是该膨胀节失效的主要原因,而局部的点蚀和残余应力、工作应力是应力腐蚀的必要条件.