首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
Problems are discussed of the combined action of phenols and metals on luminous bacteria. It is shown that the toxic effect of a mixture was not always equal to the expected additive action. An assumption is made that during a combined action phenols and metals act on the principle of competing inhibition.  相似文献   

2.
Experimental data are presented favouring a hypothesis of the elimination of quinones formed in the presence of hydroquinone oxidation in a mixture with other phenols. Results obtained on decreases of the quinone quantities in the mixture correlate with the data on a decrease of their toxicity for luminous bacteria.  相似文献   

3.
Data on the action of mono- and polyatomic phenol mixtures on hydrobionts are discussed. Luminescent bacteria, Daphnia, algae zoospores, higher aquatic plants–Elodea and duckweed – were used as test objects. It is established that the toxicity of a paired mixture of mono- and polyatomic phenols is lower than the toxicity of their components.  相似文献   

4.
A brief discussion is suggested of a possibility of employing in the practice of the analyses results on the combined action of phenols described in the preceeding parts of the work and of the interaction of the increased toxicity of phenolic compounds with the processes of their oxidation.  相似文献   

5.
Data are presented on the toxicity of hydroquinone and pyrocatechol in the presence of protein preparations possessing oxidase activity. Problems are discussed of their use as biologically active means.  相似文献   

6.
Experimental material was obtained supporting a hypothesis on the interaction between p- and o-diphenol toxicity and their oxidation. It is shown that quinones – the products of pyrocatechol and hydroquinone oxidation – possess increased toxicity towards luminous bacteria cells.  相似文献   

7.
The toxic action of bicomponent mixtures of phenols and heavy metals on luminous bacteria has been studied. It was established that phenolic compounds displaying properties of structural-specific agents whose influence is based on chemical reactions with receptors in mixtures with heavy metals of mercury, cadmium in low concentrations caused additive, and with the increase of metal concentration-more than additive, effects. Phenolic compounds acting as structurally-nonspecific agents (resorcinol), whose toxicity is stipulated by their physico-chemical properties, produce a less than additive effect in a mixture with heavy metals.  相似文献   

8.
After an outline of the possibilities and difficulties connected with the polarographic determination of aqueous quinone solutions, a specified oscillo-polarographic method of investigation is described. By the examples of solutions of pure substances as well as of the industrial waters of a pulp mill (up to 2.3 mg/1 total quinone) the conditions for applying the technique developed art' explained. The relative error of this method does not exceed 3%  相似文献   

9.
By using Nitella, with the aid of a technique which is described in detail the uptake of resorcinol by the cytoplasm was demonstrated and quantitatively determined under different test conditions. In contrast to the phenol oxidation products of hydroquinone and pyrocatechol, the further “fate” of the resorcinol taken up by the cell substance is not yet fully clear. The rate of resorcinol absorption has been defined with a permeability constant.  相似文献   

10.
The effects of oxygen supply rate and the presence or absence of nutrients on the kinetics of phenol degradation and oxygen consumption by a mixed microbial population were tested in a model system. The values for the maximum specific rate of phenol degradation (qSmax), the saturation constant (KS), and the inhibition concentration (SCR) were determined for unlimited growth (KLa = 340 h?1, growth medium) with 1.7 mmol g?1 h?1, 65 mg L?1, and 190 mg L?1. Under limitation conditions, alterations occur depending on the type of limitation. Nutrient limitations lead to values of 0.8 mmol g?1 h?1, 45 mg L?1, and 160 mg L?1, and oxygen limitations lead to 1.2 mmol g?1 h?1. 30 mg L?1, and 120 mg L?1, respectively. The results suggest that with excess oxygen, the rate of phenol degradation was higher and the inhibition effect of phenol was suppressed to some extent. Under the same high oxygen supply rate, the presence of nutrients in the model water significantly supported the phenol degradation rate.  相似文献   

11.
According to the results from investigations with different anion exchangers and synthetically obtained thiopolymers as thiopolystyrene and thiopolyvinylether, phenols and their oxidation products can be removed with different efficiencies. The individual methods of treatment and analysis are described. The results of the purification efficiency as well as the profile of the adsorption isotherms are presented in a large number of tables and figures.  相似文献   

12.
Current codes of practice in assessing the blast ground motion effect on structures are mainly based on the ground peak particle velocity (PPV) or PPV and the principal frequency (PF) of the ground motion. PPV and PF of ground motion from underground explosions are usually estimated by empirical formulae derived from field blast tests. Not many empirical formulae for PF, but many empirical formulae for PPV are available in the literature. They were obtained from recorded data either on ground surface or in the free field (inside the geological medium). Owing to the effect of surface reflection, blast motions on ground surface and in the free field are very different. But not many publications in the open literature discuss the differences of blast motions on ground surface and in the free field. Moreover, very few publications discuss the blast ground motion spatial variation characteristics. As ground motion directly affects structural responses, it is very important to study its characteristics in order to more reliably assess its effects on structures. In this paper, a validated numerical model is used to simulate stress wave at a granite site owing to explosion in an underground chamber. Using the simulated stress wave, the relations such as PPV and PF attenuation as well as spatial variation of motions on ground surface and in the free field are derived. Discussions on the differences of the characteristics of surface and free field motions are made. Results presented in this paper can be used in a more detailed assessment of ground motion effect on structures.  相似文献   

13.
A modern multi-purpose baroclinic circulation model (SELFE) has been recently extended to include the ability to simulate tsunami propagation and inundation. The core model is based on the 3-D nonlinear shallow-water wave (NSW) equations, which are solved on unstructured grids, using the finite-element method. A semi-implicit method is used to solve all equations to enhance numerical stability, thus bypassing the most stringent CFL restriction on the time step. Further aided algorithmically by an Eulerian-Lagrangian solution of the advection terms in the momentum equation and by a simple yet effective inundation algorithm, SELFE is very efficient and robust in both quasi-2-D (with two vertical layers) and 3-D modes. A quasi-2-D version of the model is being used to update and expand the characterization of tsunami hazards along the Oregon coast. As a part of a rigorous testing procedure that includes multiple types of coastal problems, we present in this paper a quantitative assessment of performance of the quasi-2-D SELFE for two challenging open benchmark problems proposed in the 3rd International Workshop on Long-wave Runup Models. Satisfactory results are obtained for both problems.  相似文献   

14.
15.
Over the past few decades, earthquake engineering research mainly focused on the effects of strong seismic shaking. After the 1999 earthquakes in Turkey and Taiwan, and thanks to numerous cases where fault rupture caused substantial damage to structures, the importance of faulting-induced deformation has re-emerged. This paper, along with its companion (Part Ⅱ), exploits parametric results of finite element analyses and centrifuge model testing in developing a four-step semi-analytical approach for analysis of dip-slip (normal and thrust) fault rupture propagation through sand, its emergence on the ground surface, and its interaction with raft foundations. The present paper (Part Ⅰ) focuses on the effects of faulting in the absence of a structure (i.e., in the free-field). The semi-analytical approach comprises two-steps: the first deals with the rupture path and the estimation of the location of fault outcropping, and the second with the tectonically- induced displacement profile at the ground surface. In both cases, simple mechanical analogues are used to derive simplified semi-analytical expressions. Centrifuge model test data, in combination with parametric results from nonlinear finite element analyses, are utilized for model calibration. The derived semi-analytical expressions are shown to compare reasonably well with more rigorous experimental and theoretical data, thus providing a useful tool for a first estimation of near-fault seismic hazard.  相似文献   

16.
In a surface water screening, 30 representative surface water samples collected from rivers, canals, and lakes in Berlin were investigated for the presence of 22 substituted phenols. The phenols selected include the 11 phenols considered as “priority pollutants” by the US Environmental Protection Agency (US-EPA). Surface water samples were extracted applying solid-phase extraction with styrenedivinylbenzene adsorbent. The recoveries, determined in spiking experiments, were between 80 % and 103 %. After derivatization with N-(tert-butyldimethylsilyl)-N-methyl-trifluoroacetamide (MTBSTFA) the samples were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). Phenol, cresols, 2-ethylphenol, 2-chlorophenol, 4-chloro-3-methylphenol, pentachlorophenol, 2-nitrophenol, and 4-nitrophenol were detected in the surface water samples at concentrations between 0.02 μg/L and 7.8 μg/L, respectively. The distribution of these residues in the Berlin surface waters showed that the phenolic residues, with the exception of pentachlorophenol and 2-ethylphenol, do not originate primarily from municipal sewage treatment plants discharges. Some of the phenols are formed naturally or occur as ubiquitous anthropogenic contaminants in the aquatic system.  相似文献   

17.
The degradation behaviour of a phenolic waste-water from coking containing easily utilizable carbon sources (volatile fatty acids), substances with toxic effects (phenols and phenolic compounds), and non-biodegradable organic substances (humic-like substances) by an adapted activated sludge is investigated depending on dissolved oxygen concentration (DO) and temperature. In addition, the degradation of an acetate model water with the same population was investigated. The investigations were carried out in a special respiration fermenter system by recording oxygen consumption in DO-static experiments. The oxygen consumption curves were subjected to linear regression analysis, and the maximum oxygen consumption rates were used for further calculations. Evaluation of the degradation kinetics was carried out with non-linear regression analysis via commercial software utilizing the Marquardt-Levenberg algorithm and which tested various kinetic models to obtain the best curve fit. It is shown that the dependence of growth on DO in acetate model water is well represented by Monod kinetics but by contrast can only be described in phenolic wastewater with acceptable goodness by Hill kinetics, modified by a maintenance term. The kinetic constants calculated for the mesophilic range (37 °C) are for the model water as follows: maximum specific growth rate = 0.218 h?1, half saturation constant with respect to oxygen = 0.297 g L?1, and for the waste-water: maximum specific growth rate = 0.387 h?1, half saturation constant with respect to oxygen = 0.013 gL?1 and maintenance coefficient for oxygen = 0.107 g g?1 h?1. For the thermophilic range (55 °C), a higher growth rate but a significant lower yield coefficient are to be observed. The kinetic constants calculated are: maximum specific growth rate = 0.8 h?1, half saturation constant with respect to oxygen = 0.14 gL?1 and maintenance coefficient for oxygen = 0.3 g g?1 h?1. Therefore, it can be concluded that the toxic effect of the biodegradable phenols causes a maintenance metabolism which leads to higher oxygen demand. The diminution of the limiting DO and the increased maintenance metabolism confirm the assumption that a higher maintenance metabolism leads to increased sensitivity with respect to the cosubstrate oxygen. It can be concluded that the experimental and mathematical methods used permit the maintenance metabolism with respect to oxygen caused by toxic substrates and milieu influences to be accurately determined.  相似文献   

18.
This work criticizes the entrenched views according to which the orientation of the principal tectonic stress axes can be determined from local (in time and space) observations of the kinematic indicators which jointly allow estimating the strain rate of a crustal block under study. The criticized approach ignores or replaces by subjective assumptions the following factors: (1) The block’s interaction with a hosting medium expressed in terms of the equilibrium conditions of the block; (2) The stress rate which (in addition to stresses) can affect the strain rate; (3)The specific macroscopic mechanical properties of the block’s material under the unknown sought stresses, including the ratio of the stress relaxation time to the period of observations. This approach, which is developed in some Solid Earth sciences and mainly in tectonophysics, is referred to in our paper as the method of local kinematic reconstruction (MLKR) of stresses. After briefly surveying the concept of forces and stresses and discussing the importance of studying the tectonic stresses, this paper refutes the MLKR notions based on general arguments and by the example of certain thought experiments. It is shown that the use of the MLKR for the conditions of the Earth’s interior does not guarantee against obtaining the results that fundamentally and drastically differ from the true tectonic stresses. In the studied rock block, depending on the factors ignored in the MLKR, the principal axes of the strain rate tensor, on one hand, and the principal stress axes, on the other hand, can be oriented discordantly in any arbitrary given fashion. In particular, in the processes accompanied by the release of elastic energy, the maximal rate of elongation can be oriented along the axis of maximal compression, whereas the maximal rate of shortening can be aligned with the axis of the maximal tension. In this paper, the deformation processes that are most detrimental to the results of stress reconstruction by the MLKR are revealed. We introduce the notion of the inherited stress-state regime in which the orientation of the axes of principal stresses during the observation period does not depend on the deformation process and, hence, cannot be in principle determined by the MLKR. An attempt to directly locally recover the stress axes from the kinematic data is a false objective because neither the physical meaning of the stress tensor nor the way it is introduced has anything to do with strains. It is concluded that the MLKR is physically inadequate and that the tectonophysical concept of locality should be abandoned in favor of returning to the notions of classical physics, namely, to using the conservation laws. By the example of several guides on tectonophysics, this paper exposes typical errors in understanding the stress reconstruction problem.  相似文献   

19.
By the example of some phenols and qninones, in aqueous solutions possibilities for the quantitative determination are tested separately and in the mixture. Methods for thin-layer chromatography and spectrophotometry were developed. There can be chromatographically deteeted between 5 and 80 μg of substance. Phenol and quinone concentrations of 1.5 · 10?3 … 0.5 · 10?4 M were spectrophotometrically investigated.  相似文献   

20.
Recent results of in situ measurements and their interest for a seismic assessment of existing buildings are presented and analysed. The present paper (Part I) is devoted to the experimental programme. The response to ambient vibrations, harmonic excitation and shock loading is recorded on intact buildings but also after their structure or their vicinity was modified. These tests aim to identify the dynamic behaviour of ordinary intact buildings built in a conventional practise. Moreover, taking advantage of their demolition, it was possible (through these tests) to determine the actual influence of the light work elements, full precast facade panels, bearing masonry walls, and the presence of neighbouring joined buildings. These experiments realized on real buildings show that information gathered from ambient measurements provide reliable and efficient data of real interest for a clear understanding of the actual building behaviour. The advantage of integrating these data in the vulnerability assessment is presented and discussed in the next paper (Part II). Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号