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41.
The primary purpose of the study was to address the claim that people are more likely to walk to a transit stop if they live on a “walkable” block. An additional purpose was to evaluate the Irvine Minnesota Inventory (IMI) as an environmental audit tool. The IMI was used to measure walkability features of 19 blocks in a revitalizing neighborhood. We hypothesized that residents who walked to a light rail TRAX stop (n = 22) would live on blocks with higher walkability ratings compared to residents who did not walk to TRAX (nonriders, n = 15), or who walked only after a closer TRAX stop was built (new users, n = 11). A MANCOVA indicated the IMI scales differentiated the blocks; the strongest differences were obtained in subscales that measured the block's diversity, safety from crime and density (marginally significant). Participants' perceptions of their complete walk to the transit stop were consistent with the home block IMI scores, with the continuing riders having more positive views than the other two groups. The results show the ability of the IMI to distinguish among blocks in walkability, and support further use of this audit tool in environmental analyses and active living research. We end with a discussion of conceptual and methodological issues in the use of audit tools and provide recommendations for using these measures for local, immediate interests, as well as for building a broader science of environmental measurement. 相似文献
42.
Adamo P Bargagli R Giordano S Modenesi P Monaci F Pittao E Spagnuolo V Tretiach M 《Environmental pollution (Barking, Essex : 1987)》2008,152(1):11-19
To enhance the reliability of the moss and lichen transplant technique for active biomonitoring of trace metals in urban environments, we evaluated the natural variability in the chemical composition of the (epilithic and epiphytic) moss Hypnum cupressiforme and the epiphytic lichen Pseudevernia furfuracea from two reference areas in NE Italy. Green shoots of epilithic mosses and lobes of epiphytic lichens from larch branches showed rather homogenous composition and were selected for the exposure in nylon bags. As different physico-chemical pre-treatments are usually applied to selected cryptogamic material before its exposure, we also evaluated the effects of oven-drying at 120 degrees C for 24h, washing in 1N HNO3 solution, and in 0.5% NH4 oxalate solution at 85 degrees C for 15 h on the chemical composition and morphology of water-washed moss shoots and lichen lobes. Pre-treatments remarkably changed the chemical composition of selected materials but not their surface morphology. 相似文献
43.
To better understand the affect of different levels of EMF on one’s brain activity, the Hodgkin–Huxley model has been used
to describe the generation of an active potential in the nerve cell membrane. The theoretical calculations have shown that
by the simultaneous affect of both passing an electrical potential and external very low frequency AC, one’s excitation pulses
may be suppressed beginning with a certain level of external current. The level of this current depends on the frequency.
It is postulated that to eliminate this suppression, the brain increases its normal level relatively to the lower limit. It
is also postulated that the brain “tunes up” in the presence of external AC, by increasing the amplitude of its own excitation
signals so that suppression does not occur. It is possible that this “tuning” process lasts some time after removing the external
EMF as the brain adapts. This has been observed experimentally. 相似文献
44.
从广州某印染厂生化处理池的活性污泥中筛选到三株对活性艳红X-3B具有高效脱色作用的真菌,其中菌株HMX-3的脱色能力最强。考察了培养时间、温度、培养方式、pH值以及染料浓度对HMX-3脱色能力的影响。结果表明,菌株HMX-3对150mg/L X-3B的24h脱色率达65.8%,经60h可使其完全脱色;HMX-3对活性艳红X-3B脱色的最适温度为25℃~35℃,最佳pH值为6~8,且振荡培养较静置培养条件下的脱色率高;随染料浓度的增加,脱色率降低,但对于400mg/L的X-3B在72h时的脱色率可达86.7%。 相似文献
45.
Yifan Wang Xiuhua Zhu Yuan Gao Hao Bai Pengyuan Wang Jiping Chen Heping Yuan Longxing Wang Xiaoxiao Li Wei Wang 《环境科学学报(英文版)》2019,31(6):287-295
The concentration of short-chain polychlorinated paraffins(SCCPs) in the urban air of Dalian,China was monitored from September 2016 to August 2017 with a self-developed passive sampler(PAS1) and an active high-volume sampler, simultaneously. PAS1 successfully collected the entire target SCCPs in the ambient air. Air SCCPs sampled by PAS1 were found be in the linear uptake stage during 181 days of sampling. Passive and active samples showed comparable congener profiles, and the dominant contributors of SCCPs in the two kinds of samples were similar. A significant linear correlation was observed between the total concentration of SCCPs sampled by PAS1 and active sampler in the four seasons. The passive sampling rates of the PAS1 for the gas and particulate phases of SCCPs were measured. The quantitative structure–property relationship of the sampling rate of PAS1(Rair) for gas-phase SCCPs was studied. From the molecular point of view, Rairwas mainly affected by the molecular weight and sub-cooled liquid vapor pressure of SCCPs. In general, SCCPs in the urban air of Dalian mainly existed in gas phase,lower molecular weight SCCPs primarily occurred in the gas phase, whereas higher molecular weight SCCPs were predominately adsorbed or absorbed on airborne particles. The air concentration of SCCPs in the four seasons were different, the correlation of the concentration of SCCPs in the air with the meteorology parameters was conducted. The exposure risk by intake air SCCPs of the residents around the sampling sites was evaluated according to the European risk assessment standards. 相似文献
46.
蒋超 《中国特种设备安全》2013,(12):25-26
由于技术的进步和生产要求的提高.变频技术被越来越多的使用在包括港口起重机械在内的起重设备中。在提高整机性能的同时,大量谐波的出现也给起重设备的运行带来较大危害。本文针对某港口出现的谐波问题,采用了有源滤波器对谐波进行处理,取得了良好的效果,具有广阔的应用前景。 相似文献
47.
48.
三维粒子电极催化氧化活性艳红X-3B实验研究 总被引:2,自引:1,他引:1
采用浸渍焙烧法制备了Cu/γ-Al2O3、Cu-Co/γ-Al2O3粒子电极,TiO2/Ti为阳极、石墨为阴极,采用三维电极降解染料模拟废水活性艳红X-3B溶液,考察了粒子电极、槽电压、pH值、电解质浓度等因素对处理效果的影响。实验结果表明:该反应器能够有效的降解X-3B,粒子电极显示了较高的催化活性,双组分粒子电极Cu-Co/γ-Al2O3比单组分粒子电极Cu/γ-Al2O3有着更好的催化效果,降解机制主要是电致·OH的间接氧化和粒子电极表面的直接氧化的协同作用。 相似文献
49.
50.
Most studies on insect sperm motility have been conducted in vitro using artificial environments outside the animal’s body.
Only little is known about the function of motile insect sperm at different sites within the male or female genital tracts.
We dissected genital tracts of female rove beetles (Drusilla canaliculata) to show that spermatozoa use their own motility to migrate from the spermatophore into the spermatheca. Our dissection method
allowed direct observation and filming of the spermathecal filling process inside the female’s genital tract. Spermatozoa
were found to enter the spermatheca individually, sometimes in groups of two or three. Although exhibiting only weak motility
and no progressive motion in buffer solution, the spermatozoa inside the female show vigorous lashing and reach an average
velocity of 47.5 μm s−1. To gain mobility and speed, the spermatozoa likely utilize the relatively small diameter of the spermathecal duct to push
themselves off the duct walls, rather than swimming freely in seminal fluid. The spermatozoa (approximately 1,250 μm) are
considerably longer than the distance they have to travel along the spermathecal duct (approximately 800 μm). Our study provides
the first direct observation of active sperm migration within the female of an insect stressing the importance of the genital
tract as a prerequisite for functional sperm motility. 相似文献