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11.
In the recent years concerns whether exposure to electromagnetic fields (EMF) from base station antennae can cause adverse
health effects are grown. Great attention is paid on risk of EMF exposure to people living in a close proximity of base stations.
In this issue, a point of interest is the personnel mounting, adjusting and maintaining base stations. Their working tasks
require stay in high EMF levels’ conditions. There are only few studies concerning this specific occupational group. The results
from our previous investigation (COST 281—Graz, 2006) show that in many cases on performing some specific tasks operators
are overexposed according to our national legislation, and ICNIRP guidelines. Here, we present an extended study covering
more base stations and more precise scenario for performed tasks and working positions. Results of exposure assessment are
presented. They include energetic load calculations on the basis of Bulgarian national legislation, and the corresponding
SAR values. Data are used to determine permissible time duration for each particular work operation and served as a base for
limiting the exposure and proposal for protective measures for the personnel. 相似文献
12.
Investigators monitoring air quality at the World Trade Center, after the September 11th attacks, found extremely high levels
of volatile organic chemicals as well as unusual species that had never been seen before in structure fires. Data collected
by the U.S. Environmental Protection Agency indicate striking spikes in levels of benzene, styrene, and several other products
of combustion. These spikes occurred on specific dates in October and November 2001, and February 2002. Additionally, data
collected by researchers at the University of California Davis showed similar spikes in the levels of sulfur and silicon compounds,
and certain metals, in aerosols. To better explain these data, as well as the unusual detection of 1,3-diphenylpropane, the
presence of energetic nanocomposites in the pile at Ground Zero is hypothesized. 相似文献
13.
为有效抑制纳米级Pd/Fe颗粒的团聚和钝化及改善磁分离效果,以多壁碳纳米管(MWCNTs)和磁性纳米级Fe_3O_4颗粒为载体,在超声波辐照下利用液相还原法制备纳米级Pd/Fe-MWCNTs-Fe_3O_4颗粒,并采用XRD、TEM、SEM、EDX及BET表征其物性,最后以2,3-二氯联苯(2,3-DCB)为目标污染物,探究其对2,3-DCB还原脱氯的影响因素、降解机理和动力学.结果表明:制备的纳米级颗粒粒径均匀、分散性好、比表面积大;体系中纳米级Pd/Fe投加量、钯化率、纳米级Fe_3O_4投加量、MWCNTs投加量、反应温度、溶液初始pH及共存阴离子均会对2,3-DCB的降解效果产生明显影响;本研究推测出纳米级Pd/Fe-MWCNTs-Fe_3O_4体系对2,3-DCB的降解机理,发现其降解符合拟一级动力学关系. 相似文献
14.
Nickel oxide nanoparticles decorated carbon nanotube nanocomposites(Ni O·CNT NCs)were prepared in a basic medium by using facile wet-chemical routes. The optical,morphological, and structural properties of Ni O·CNT NCs were characterized using Fourier transformed infra-red(FT-IR), Ultra-violet visible(UV/Vis) spectroscopy, field-emission scanning electron microscopy(FESEM), X-ray energy dispersed spectroscopy(XEDS), X-ray photoelectron spectroscopy(XPS), and powder X-ray diffraction(XRD) methods. Selective4-aminophenol(4-AP) chemical sensor was developed by a flat glassy carbon electrode(GCE, surface area: 0.0316 cm~2) fabricated with a thin-layer of NCs. Electrochemical responses including higher sensitivity, large dynamic range(LDR), limit of detection(LOD), and long-term stability towards 4-AP were obtained using the fabricated chemical sensors. The calibration curve was found linear(R~2= 0.914) over a wide range of 4-AP concentration(0.1 nmol/L–0.1 mol/L). In perspective of slope(2 × 10~(-5)μA/μM), LOD and sensitivity were calculated as 15.0 ± 0.1 pM and ~ 6.33 × 10~(-4)μA/(μM·cm) respectively. The synthesized Ni O·CNT NCs using a wet-chemical method is a significant route for the development of ultrasensitive and selective phenolic sensor based on nano-materials for environmental toxic substances. It is suggested that a pioneer and selective development of 4-AP sensitive sensor using Ni O·CNT NCs by a facile and reliable current vs voltage(I–V)method for the major application of toxic agents in biological, green environmental, and health-care fields in near future. 相似文献
15.
16.
Michael E. Fraker 《Behavioral ecology and sociobiology》2008,62(7):1201-1205
The activity level of prey reflects a trade-off between predation risk and foraging gain. A number of theoretical and empirical
studies have shown that a prey's energetic state or the level of its resource should influence this trade-off (i.e., what
the optimal activity level at a level of predation risk is). Here, I show that the energetic state of prey may also influence
the duration of their antipredator behavioral response. Green frog tadpoles (Rana clamitans) reduced their activity level for a shorter time during exposure to the chemical cue of predatory larval dragonflies (Anax spp.) as their time since last feeding increased (i.e., as their energetic state decreased). Interestingly, the tadpoles
strongly reduced their activity level upon cue exposure in all treatments. Thus, the relative activity level of tadpoles at
different energetic states varied over time. 相似文献
17.
以钛酸四丁酯为钛源,甘氨酸为模板剂,水热法合成纳米TiO2/CuO复合材料,采用XRD、SEM、FT-IR、XPS、UV-VIS DRS等分析手段对TiO2/CuO复合材料的晶型结构、形貌、粒径及组成进行表征.结果表明,XRD、SEM证实TiO2/CuO复合材料由锐钛矿型TiO2和CuO组成,形貌呈花瓣薄片状纳米花球,花瓣厚约15 nm;FT-IR、XPS表明其含有Ti—O键和Cu—O键,且Ti呈+4价、Cu呈+2价;UV-VIS DR显示其在紫外-可见光区具有显著的光吸收能力.相比P25型TiO2,TiO2/CuO复合材料具有较好的光催化性能,光催化降解亚甲基蓝(MB)的效率高达85%.这可能由于TiO2/CuO复合材料具有宽的可见光区域和窄的带隙,以及CuO对电子的捕获,促进了光生电子和空穴有效分离. 相似文献
18.
This work aims to characterize and develop a disposal method for a gel-like deposit generated in a vacuum foreline of an atomic layer deposition (ALD) tool that is using hexachlorodisilane (Si2Cl6, HCDS) as a precursor. This ALD foreline gel was reproduced by replicating the ALD tool process conditions by using a benchtop system that was a 1/85 scale down of one user's process. All samples were tested for shock sensitivity using the Fall hammer apparatus. Extensive infrared studies were done for unhydrolyzed and hydrolyzed gel. Dissolution tests were conducted to develop a method for removing and disposing the gel off-site. Many different solutions such as solvent based solutions, water based alkaline solutions and alcohol based alkaline solutions were tested. It was found that alcohol based alkaline solutions produced only hydrogen as a byproduct and were considered satisfactory for off-site abatement of gel. Furthermore, in-situ cleaning gel of the foreline using a fluorine/N2 mixture with a concentration of 1–10vol% was done. They were all effective in cleaning/removing the gel under the condition of ambient temperature and reduced pressure. Finally, recommended procedures were given for removing as well as disposing the ALD gel. 相似文献
19.
凹凸棒石/氧化锌纳米复合材料对亚甲基蓝的吸附性能 总被引:4,自引:1,他引:4
采用化学沉淀法在凹凸棒石的表面负载纳米氧化锌合成了凹凸棒石/氧化锌(ATP/ZnO)纳米复合材料.同时,研究了亚甲基蓝在纳米复合材料上的吸附行为,并从热力学和动力学角度探讨了吸附作用机理.吸附实验表明:纳米复合材料对亚甲基蓝有优异的吸附能力;纳米复合材料对亚甲基蓝的吸附热力学符合Langmuir等温吸附方程,最大吸附量可达110.50mg·g-1,吸附焓变为18.69kJ·mol-1,吸附自由能变为-33.06~-22.74kJ·mol-1,吸附熵变约为146J.mol-1.K-1,是一个自发的吸热过程;纳米复合材料对亚甲基蓝的吸附动力学符合准二级动力学方程,速率常数随着溶液初始浓度的提高而下降. 相似文献
20.
Zahra Bahri-Kazempour Khosro Abdi Mojtaba Shakibaie Hamid Forootanfar Hossein Attar 《毒物与环境化学》2013,95(1):118-126
In this investigation, Fe3O4 magnetic nanoparticles (MNPs) were prepared by the alkalinization of an aqueous medium containing ferrous sulfate and ferric chloride. In the next step, a Fe3O4–AgCl magnetic nanocomposite was fabricated by the drop-by-drop addition of silver nitrate solution into a NaCl solution containing Fe3O4 MNPs. All prepared nanoparticles were characterized by transition electron microscopy (TEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). Both particle types varied in size from 2.5 to 20?nm, with an average size of 7.5?nm for Fe3O4 MNPs and 12.5?nm for Fe3O4–AgCl nanocomposites. The antibacterial effect of the Fe3O4 MNPs and fabricated Fe3O4–AgCl nanocomposites against Escherichia coli (ATCC 35218) were investigated by conventional serial agar dilution method using the Müller–Hinton Agar medium. The minimum inhibitory concentration was 4?mg?mL?1 for Fe3O4 MNPs and 2?mg?mL?1 for the Fe3O4–AgCl magnetic nanocomposites. Time-kill course assays showed that the Fe3O4–AgCl magnetic nanocomposites successfully killed all inoculated bacterial cells during an exposure time of 60?min. The antibacterial activity of recycled Fe3O4–AgCl magnetic nanocomposites over four 60?min cycles of antibacterial treatment was further tested against E. coli by the colony-forming unit (CFU) method. The antibacterial efficiency of the nanocomposites was constant over two cycles of antibacterial testing. 相似文献