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161.
Zeinab Tavasoli Parviz Abdolmaleki Seyed Javad Mowla Faezeh Ghanati Amir Sabet Sarvestani 《The Environmentalist》2009,29(2):220-224
This research was carried out to evaluate the influence of static magnetic field on the rate of apoptosis in bone marrow stem
cells (BMSCs) of rats. Extracted cells were suspended in αMEM as a culture media for 48 h. After that, cells were exposed
to 15 mT static magnetic field (SMF) for 5 h, incessantly with or without FeCl2. The rate of apoptosis was then assessed via flow cytometery. The results showed that either treatment with FeCl2 or exposure to SMF enhanced the rate of apoptotic cells. Moreover, cells that were treated simultaneously with FeCl2 and SMF have higher rate of apoptosis. An increase in apoptosis by 26.5% was induced by SMF alone and an increase in apoptosis
by 28.2% was induced by a combination of FeCl2 and SMF, compared to their corresponding controls. The results recommended that the effects of SMF on apoptosis may be related
to increment of the number of free radicals in the cells. 相似文献
162.
Experimentally induced acute inflammation in rats is a good model system which includes the complexity and dynamics of the
processes; moreover there are many defined markers for following and estimating changes in an observed system. In this paper,
we discuss an in vivo model of acute inflammation induced by carrageenan. Carrageenan-induced paw edema is a model of non-infectious
acute inflammatory reaction to assess the contribution of mediators involved in vascular changes associated with acute inflammation
and potential treatments. A complex approach into the investigation of possible effects of static magnetic fields (SMF) action
on experimentally induced acute inflammation in rats (by measurements of the levels of specific stress markers) is very important
in understanding the possible inflammatory mitigation effects, pain relief, and oxidative stress state of an organism. This
approach could help for better understanding of the possible mechanisms of interaction of dynamic processes such as inflammation
healing and pain relief with external SMF (25 mT at 10, 20 and 30 min exposure time). Results indicate that SMF with B = 25 mT
for 30 min diminished the inflammatory process and decreased the levels of inflammatory markers (fibrinogen) and stress markers
(ACTH, Cor) into the blood plasma in rats as when compared with sham exposed animals. The exact mechanism by which SMF contributes
to the acceleration of inflammatory healing and decrease of inflammation markers in blood plasma in rats still remains unclear.
We assume that two possible mechanisms exist. One is the direct interaction of SMF with free active oxygen forms (free radicals)
affected by their membrane processes and related with the physiological functions. Another possible mechanism might be related
to dynamic regulation of inflammation healing process. 相似文献
163.
164.
Groundwater over-pumping is a major problem in several countries around the globe. Since controlling groundwater pumping through water flow meters is hardly feasible, the surrogate is to control electricity usage. This paper presents a framework to restrict groundwater pumping by implementing an annual individual electricity quota without interfering with the electricity pricing policy. The system could be monitored online through prepaid electricity meters. This provides low transaction costs of individual monitoring of users compared to the prohibitive costs of water flow metering and monitoring. The public groundwater managers' intervention is thus required to determine the water and electricity quota and watch the electricity use online. The proposed framework opens the door to the establishment of formal groundwater markets among users at very low transaction costs. A cost–benefit analysis over a 25-year period is used to evaluate the cost of non-action and compare it to the prepaid electricity quota framework in the Batinah coastal area of Oman. Results show that the damage cost to the community, if no active policy is implemented, amounts to (−$288) million. On the other hand, the implementation of a prepaid electricity quota with an online management system would result in a net present benefit of $199 million. 相似文献
165.
1990年以来,随着中国电力体制改革的深入,电力基础设施与经济同步发展。由于电力生产与电力消费存在着显著的空间差异,电力发展对经济增长的影响可能存在空间差异。本文利用1990—2011年省级面板数据,基于增长回归模型,采用动态面板分析方法,以电力投资率和发电装机容量作为衡量电力发展的指标,检验电力发展对经济增长的影响以及这种影响的区域间差异。实证研究的主要发现如下:首先,电力发展对经济增长有显著的正面影响,而且其长期影响明显高于短期影响。其中,电力投资率每增加1个百分点,短期经济增长率提高0.076个百分点,长期经济增长率提高0.493个百分点;发电装机容量每增加1个百分点,短期经济增长率提高0.381个百分点,长期经济增长率提高1.905个百分点。其次,电力发展对经济增长的影响具有显著的地区差异,对东部地区的经济增长影响显著高于西部地区。其中,电力投资率增加1个百分点对东部地区的经济增长率影响高于西部地区达0.913个百分点;电力装机容量增加1个百分点对东部地区的经济增长率影响高于西部地区达0.959个百分点。实证结果表明,电力发展对各地区经济增长影响是不平衡的,这种影响对区域经济协调发展起到了负面作用。基于实证研究,给出如下政策建议:首先,考虑到中国经济在未来20年中仍将保持较高增速,中国应继续促进电力发展投资,以促进经济增长。其次,从政策导向来看,电力发展政策应当充分加强电力发展对区域协调发展的作用,使得西部地区能从电力输出中获得更高收益,提高电力发展对区域经济增长影响的公平性。 相似文献
166.
社会技术转型的多层视角(MLP)是转型理论的最新进展,它认为转型是由三个层面——微观层的技术利基,中观层的社会技术体制和宏观层的大环境——相互作用引起的一个非线性的演化过程。该思路通过分析技术和社会因素之间的互动关系,寻求理解社会技术体制的长期变化。本文以MLP为分析思路,研究我国电力系统现行体制已经发生的动态变化;并从短期,中期和长期三个时间维度,对我国低碳电力系统转型路径提出一个概念性的分析框架。短期的转变路径,延续和发展现有体制结构和治理模式,通过体制内行为主体有意识地调整创新活动和发展的方向,来解决体制内部矛盾和压力,实现政府2020年的减排目标和可再生能源目标。中期的重构路径,基本实现电源结构实质性改变,火力发电比例逐步下降,可再生能源发电对其主导地位形成冲击和挑战,电力系统呈现百花齐放百家争鸣之势态。长期的重置路径通过新的低碳能源技术创新的质的突破和飞跃,实现高煤高碳的电力体系由新的低碳体制取代这一长期目标。本文从理论和方法上丰富了目前我国低碳转型的讨论,对政策制定者和相关的行为主体也可提供一种有益的参考。 相似文献
167.
构建了单室空气阴极微生物燃料电池(MFC),研究了苯酚含量对以苯酚和葡萄糖为底物的MFC产电性能及苯酚去除率的影响。实验结果表明:当CODB(苯酚贡献的COD)为0时,MFC的运行周期为36 h,最大输出电压为560 m V,最大功率密度为489 m W/m2;CODB为1 000 mg/L时,MFC的运行周期为54 h,最大输出电压为436 m V,最大功率密度为98 m W/m2;当CODB为200 mg/L时,MFC的COD去除率、苯酚去除率和库伦效率(CE)均达到最大,分别为89.7%、99.9%和7.2%,同时,MFC的阳极生物膜产生的氧化峰电流最高,表明在葡萄糖-苯酚双底物对微生物的协同作用下,MFC的阳极生物膜氧化性最强;随着CODB的增大,COD去除率、苯酚去除率和CE均逐渐减小,说明苯酚的抑制作用导致微生物活性降低。 相似文献
168.
Iftheker A. Khan Nirupam Aich A.R.M. Nabiul Afrooz Joseph R.V. Flora P. Ariette Schierz P. Lee Ferguson Tara Sabo-Attwood Navid B. Saleh 《Chemosphere》2013
Aggregate structure of covalently functionalized chiral specific semiconducting single-walled carbon nanotubes (SWNTs) was systematically studied employing static light scattering (SLS). Fractal dimensions (Df) of two specific chirality SWNTs—SG65 and SG76 with (6, 5) and (7, 6) chiral enrichments—were measured under four biological exposure media conditions, namely: Dulbecco’s Modified Eagle Medium (DMEM), Minimum Essential Medium (MEM), Roswell Park Memorial Institute (RPMI) 1640 medium, and 0.9% saline solution. The SWNTs exhibited chiral dependence on Df with SG65 showing more fractal or loosely bound aggregate structures, i.e., lower Df values (range of 2.24 ± 0.03 to 2.64 ± 0.05), compared to the SG76 sample (range of 2.58 ± 0.13 to 2.90 ± 0.08). All the Df values reported are highly reproducible, measured from multiple SLS runs and estimated with ‘random block-effects’ statistical analysis that yielded all p values to be <0.001. The key mechanism for such difference in Df between the SWNT samples was identified as the difference in van der Waals (VDW) interaction energies of these samples, where higher VDW of SG76 resulted in tighter packing density. Effect of medium type showed lower sensitivity; however, presence of di-valent cations (Ca2+) in DMEM and MEM media resulted in relatively loose or more fractal aggregates. Moreover, presence of fetal bovine serum (FBS) and bovine serum albumin (BSA), used to mimic the in vitro cell culture condition, reduced the Df values, i.e., created more fractal structures. Steric hindrance to aggregation was identified as the key mechanism for creating the fractal structures. Also, increase in FBS concentration from 1% to 10% resulted in increasingly lower Df values. 相似文献
169.
170.