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601.
G. Duranti A. Rossi N. Rosato G. Fazio G. Sacerdoti P. Rossi R. Falsaperla V. Cannelli R. Supino 《The Environmentalist》2005,25(2-4):113-119
Summary The biological effects of electromagnetic radiation at ultra high frequency on human keratinocytes were investigated. HaCaT
cell system, a spontaneously immortalized human keratinocytes cell line, was chosen as model since skin is usually exposed
to electromagnetic radiation at considered frequency more than inner tissues. HaCaT cells were exposed to a pure sinusoidal
field at a frequency of 900 MHz (average SAR levels ranging from 0.04 to 0.08 W/kg) in plane wave condition inside a GTEM
chamber for time intervals of 18 hours at a controlled temperature of 37∘C. Growth curves were obtained for exposed and control cells, and a reduction in the number of exposed cells in comparison
to unexposed ones was found; however the number of dead cells was not significantly different in exposed and unexposed samples.
In order to investigate whether the reduction in cell proliferation of exposed cells was due to the activation of a differentiative
process, the expression of two hallmarks of differentiation was examined. Both keratin 1 and involucrin expression was increased
in exposed in comparison to unexposed cells. These results suggest that this protocol of exposure to 900 MHz electromagnetic
field can trigger a differentiation program in HaCaT cells. 相似文献
602.
Summary Since IARC classified ELF magnetic field as Possibly Carcinogenic to Human the fear from 50/60 Hz magnetic field exposure
had been increased to the state of public “panic”. Subsequently, environment quality preservation organizations increased
their pressure on their government to adopt the “precautionary principle” and to reduce the allowable ELF Magnetic Field exposure
to much lower values than are recommended by ICNIRP-1998. As an example the present Environmental Ministry in Israel recommendation
is to lower the ELF Field exposure to 10 mG averaged over 24 h.
As a result of this stringent exposure guideline imposed by the government, electrical engineers who are involved in the deployment
and installation of large and medium electrical utilities, such as overhead power lines, transformers, UPS systems, electrical
public transportation, switching stations, etc., are much more aware to the need to employ special measures and methods for
reducing the magnetic fields that might be emitted from such utilities.
There are few computer codes that are capable of analyzing with great accuracy magnetic and electric fields surrounding single
phase and three phase electrical utilities in a 3-D system. The best presentations of the analysis results are by equi-value
contours depicting electric and magnetic fields. This graphical presentation is a powerful design tool that enables better
deployment and installation design aided to reduce the magnetic field emissions from high-power electrical utilities.
This paper describes the various types of graphical presentations available for ELF field contours, the dependent and independent
variants and parameters, magnetic field animation for optimization of power line installation and routing, and finally an
example that demonstrates the usefulness of the graphical presentation tools. 相似文献
603.
604.
范春梅 《中国环境管理干部学院学报》1999,(3)
清初“摊丁入亩”政策对清社会经济的恢复发展确实起到了促进作用,但同时对环境也构成了巨大威胁,引发了地表植被遭严重玻坏、自然灾害频繁、珍稀野生动植物大量灭绝等一系列环境问题。剖璞见玉,对今有史鉴作用。 相似文献
605.
N. A. Belova O. N. Ermakova A. M. Ermakov Z. Ye. Rojdestvenskaya V. V. Lednev 《The Environmentalist》2007,27(4):411-416
We report the results of a study of the influence of extremely-weak alternating magnetic fields (EW AMF) directed co-linearly
to the static Earth’s magnetic field on the rate of regeneration in planarians and also on the rate of gravitropic response
in the stem segments of flax. In particular we obtained the data on the dependence of the value of bioeffects on the amplitude
(at fixed 60 Hz—frequency) and on the frequency (at fixed 1.6 μT—amplitude) of the alternating component. Our data show unambiguously
that EW AMF substantially affect the properties of the biosystems. The experimental data may be approximated by the theoretical
expression following directly from a general formula, derived in the theory of magnetic parametric resonance. Our data indicate
that the nuclear spins of hydrogen atoms serve as the primary targets for the action of the EW AMF on the biosystems. The
values of bioeffects of combined magnetic fields with extremely weak alternating component are completely determined by the
parameter , where γ = 42.578 Hz/μT—gyromagnetic ratio of the nuclear spins of hydrogen atoms, and and f correspond to magnetic induction and frequency of the alternating magnetic component. The dependence of bioeffect’s
value on —parameter is polyextremal: well expressed maxima are observed at and minor maxima at . The bioeffects are absent at , 3.8, 5.3, 6.7. At the values of the bioeffect changes its sign—activation of planarian’s regeneration starts to be replaced by its inhibition. The inhibition
takes place for the range of the amplitudes from 10 to 140 μT. The observed change in the sign of the effect may result to
the prevalence of the effects caused by the induction of the alternating currents in the test-system at relatively high —amplitudes. These results provide the basis for planning of the epidemiological studies and interpretation of the corresponding
results. 相似文献
606.
A. I. Fiaschi D. Cerretani E. Battisti L. Bianciardi N. Giordano A. Albanese 《The Environmentalist》2009,29(2):200-204
Osteoarthritis (OA) is the most common joint disorder, associated with loss of articular cartilage, osteophyte formation,
subchodral bone change, synovitis and characterized by chronic and often disabling pain and stiffness of one or more joints.
The pathogenesis of the disease is complex and still debated, even if recent studies have shown that reactive oxygen species
may participate in the initiation and progression of OA. Moreover, it is known that pulsed electromagnetic fields are useful
in the OA treatment, owing to their analgesic and anti-inflammatory properties. This work evaluated lipid peroxidation, glutathione,
and ascorbic acid levels in patients with OA of spine, before and after the application of a new electromagnetic system, the
TAMMEF (Therapeutic Application of a Musically Modulated Electromagnetic Field) system. In TAMMEF system, the extremely low
frequencies electromagnetic field is piloted by a musical signal and its parameters (frequency, intensity, waveform) are modified
in time, randomly varying within the respective ranges: so all possible codes can occur during a single application. Twenty
patients affected by OA of spine and 20 healthy subjects were enrolled in this study. Plasma levels of ascorbic acid (AA),
glutathione (GSH) and malondialdehyde (MDA) (as index of lipid peroxidation) were determined in patients and controls, before
the beginning of treatment (first day of therapy) and at the end of cycle. All patients underwent a cycle of 10 daily sessions
of 30 min each. Our study showed a significant increase of MDA level and a significant decrease of both AA and GSH levels
in patients with OA compared to control group. These findings support the role of oxidative stress in the pathogenesis of
OA. After TAMMEF treatment in the OA group, analysis revealed a significant decrease in plasma MDA and AA levels (P < 0.05 and P < 0.01, respectively), no significant difference in GSH levels. Reduction in MDA level could be due to the decreased generation
of reactive oxygen species and/or to the increased detoxification activity mediated by GSH. No significant difference in GSH
levels, evidenced in OA patients after TAMMEF treatment, could be due to effect sparing of AA on GSH. Furthermore, a beneficial
symptomatic effect was observed in all patients. 相似文献
607.
Eleni?NanouEmail author Chrissanthi?Hountala Argiro?Maganioti Charalabos?Papageorgiou Vassilis?Tsiafakis Andreas?Rabavilas Christos?Capsalis 《The Environmentalist》2009,29(2):205-209
The present study investigated the influence of electromagnetic fields (EMF), similar to that emitted by mobile phones, on
brain activity. Ten women and ten men, matched for age and educational level, performed a short memory task (Wechsler test),
with simultaneous Electroencephalogram (EEG) recordings at 15 scalp electrodes, both without (baseline) and with exposure
to an 1,800 MHz signal. The EEG energy was found concentrated at the four basic EEG bands [α (8–13 Hz), β (14–30 Hz), δ (0–4 Hz), and θ (5–7 Hz)]. The analysis revealed that in the presence of EMF, the energy of the β band was significantly greater for females than for males at the majority of the electrodes. Since beta oscillation is associated
with the shift of attention during the perception, these findings may indicate that the particular EMF (1,800 MHz signal)
exerts an influence on this brain activity, which appears to be gender-related. 相似文献
608.
Iodine Deficiency Disorders (IDD) are a common health problem prevalent in the wet zone of Sri Lanka with a prevalence of >25 of the population. In comparison, in the dry zone of Sri Lanka IDD occurs in <10 of the population. Seventy soil samples from 14 villages selected on the basis of the incidence of goitre, were collected and analysed for 13 trace elements using ICP-MS. In order to identify any prevailing differences in antecedent chemical environments, soil samples from each pre-selected village were classified into three groups in terms of their geographical location. Among the elements investigated, the total soil concentrations of Rb, Sr, Ba, Mn and Co are lower in the wet zone of Kalutara. In contrast, total soil Rb, Sr, Ba and Mn contents are higher in the dry zone of Anuradhapura. Further soil total Mo and Nb levels are relatively similar in all pre-selected study locations. The high endemic goitre regions (IDD >25 of the population) show low levels of Rb, Sr, Ba, and Mn and higher levels of V, Cr, Co, Ni, Cu, Zn and Pb as compared with moderate and non-goitre areas. Factor analysis was used to exploit the correlation structure present in data and yielded three groups in all cases. This indicated that most transition group elements and iodine are associated with the Mn phase in the low IDD areas whereas iodine shows a high affinity for the organic phase in high IDD regions. The variable distribution of trace elements, therefore, must be due to differences in mobility and capacity for incorporation into the structure of secondary minerals or organic phases. 相似文献
609.
珠江三角洲粘质水稻土的肥力水平和产量水平与土壤结构特性密切相关。中低产水稻土产量偏低的原因主要是5—2、2—1、1—0.5mm水稳性团聚体、1—0.01mm粗粒微团聚体和非毛管孔隙都较少,从而导致土壤通透性差,水稻生长不良。水旱轮作、犁冬晒白和增施有机物料都能在一定程度上改善土壤结构孔隙。因而促进水气循环、土壤活化、产量提高。特别是水旱轮作与施用有机物料相结合,对改善粘质中低产水稻土结构的效果最为显著。犁冬晒白对改善土壤结构和促进水稻生长发育,当季效果也很明显,但其作用不能持久,宜与其它两种措施配合使用。 相似文献
610.
长江中游土壤潜沼化现状及其利用 总被引:2,自引:0,他引:2
讨论了长江中游地区土壤潜育化沼泽化现状,土壤渍害的原因及其危害,并总结提出了一些改良措施。该地区土壤潜育化沼泽化十分普遍,四湖地区处于这种状况下的水稻土达84%,洞庭湖地区达51%,内外排水不畅是产生土壤渍害的重要原因。土壤渍害的产生极为频繁,并强烈影响作物的产量。从整个区域出发,综合考虑水利设施的规划以及因地制宜、因时制宜采取合理而有效的土壤改良措施,是改造潜沼化低产土壤的原则。 相似文献