Features of disinfection kinetics of water containing <Emphasis Type="Italic">Escherichia Coli</Emphasis> in conditions of hydrodynamic cavitation

The paper has investigated the disinfecting effect of hydrodynamic cavitation on the microorganisms of E. coli in water. It has been found that disinfection kinetics depend on the intensity of the hydrodynamic cavitation field, the microbial load, and gas content. We have studied structure and morphology variation of the E. coli bacteria. It has been demonstrated that the antimicrobial effect is achieved owing to the physicochemical effects of the cavitation field, under whose influence there occurs mechanical destruction of cells and chemical disinfection by the radicals of hydroxyl and hydrogen peroxide.     

The direct measurement of ppm levels of uranium in soils using high-resolution Ge(Li) gamma-ray spectroscopy

The direct determination of ²³⁸U in various soil samples was done by measuring the 63.3-keV transition from the decay of the first daughter ²³⁴Th. Potential errors resulting from the chemical non-equilibrium of ²³⁸U with its daughters are thus avoided. The method sensitivity is 1 ppm compared to the 35 ppm obtainable by employing the 1001-keV gamma ray. A Ge(Li) gamma-ray spectrometer is the only analytical tool required. Examples are offered that demonstrate the usefulness of the technique for routine, inexpensive environmental monitoring of uranium. The technique also has the capability of providing information on the ²³⁸U/²³⁵U isotopic ratio.     

Noise impact caused by electrical energy substations in the city of Curitiba, Brazil

This survey is intended to characterize the noise impact due to electrical energy substations in the city of Curitiba over the population living in their vicinity. This impact has been studied with the aid of a computational tool capable of mapping the acoustical field of substations and their vicinity. Several factors have been considered in this survey: (1) sound power of the transformers; (2) vehicle flow on the surrounding roads; (3) positioning of the firewalls, buildings and walls; and (4) terrain topography. Four substations have been analyzed, and an acoustical map has been traced for each of them. With these maps it was possible to visualize what was the incident noise level on the building facades. The predicted noise levels have been compared to the environmental legislation of the noise emissions in effect in the city.     

Endogenising demand for information in road transport

In this paper, the impact of endogenous information provision to drivers in road transport is investigated. A static economic equilibrium model is used, which allows potential road users to buy information on the prevailing (stochastic) traffic situation. It takes for granted that an individual will try to acquire proper information when the private benefits of doing so exceed the private costs. By using an information model for road users, the interesting result is found that the provision of endogenous information leads to a strict Pareto improvement. Furthermore, the model shows that — depending on the price of information — it can be efficiency improving to subsidise or tax the motorist information to the user. Finally, there is a relationship between fine congestion pricing and subsidising motorist information. It turns out that the social welfare maximising subsidy under first-best congestion pricing is equal to zero. However, subsidising information may be an attractive policy instrument when a flat congestion pricing scheme is preferred.Participates in the VSB-fonds sponsored research project Transport and Environment     

Structural reliability software at the University of California, Berkeley

The paper provides an overview of three software for structural reliability analysis developed at the University of California, Berkeley. These are CalREL, which is a general-purpose structural reliability code written in FORTRAN; FERUM, which is a collection of Matlab^® files that can be used for structural reliability analysis in conjunction with simple finite element models; and OpenSees, which is an object-oriented code for nonlinear structural response simulation with reliability capabilities. Reliability analysis methods featured by these software include FORM, SORM, Monte Carlo simulation, and various importance sampling methods. In addition, variable importance and sensitivity measures are provided.     

Predictions of nitrate diffusion in sediment using horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry

Using a novel and simple method based on horizontal attenuated total reflection (HATR) by Fourier transform infrared (FTIR) spectrometry, the effective diffusion coefficient, De, of nitrate in a contaminated anthropogenic sediment was estimated as 7.34 x 10(-6)cm2 s(-1). This method, which requires as little as 1 mL of sediment sample, was able to measure the De of a chemical species with a reproducibility of +/-3% in about 5h. Based on this De and a pre-determined nitrate reduction rate, the profiles of nitrate concentration in two sediment columns were satisfactorily predicted from a mathematical model. Results showed that the profile in this aged sediment depended mainly on the diffusion of nitrate and, only to a much lesser degree, the rate of nitrate reduction. Measurements in 55 anthropogenic sediment samples collected from five locations and various depths of a contaminated site further showed that the De of nitrate increased linearly with the water content of the sediment, but decreased with the sediment density. The technique demonstrated in this study shall be applicable for the risk assessment of toxic pollutants in contaminated sediments, and for planning the spatial and time intervals of nitrate injection strategy in bioremediation.     

Speciation of selenium in plant water extracts by ion exchange chromatography-hydride generation atomic absorption spectrometry

Determination of selenium (Se) speciation in plants is important in studying the bioavailability and toxicity of Se in Se-contaminated soil/sediment. In this study, we used an anion exchange resin (Dowex 1-10X) to separate Se into non-amino acid organic Se, Se-amino acids, selenite (Se [IV]) and selenate (Se [VI]) in a plant (Stanleya pinnata) extract. The hydride generation atomic absorption spectrometry (HGAAS) was used to determine concentrations of these Se compounds in plant extracts. Results showed that Se compounds can be quantitatively separated by the resin column. Recovery of five spiked standard Se compounds (trimethylselenonium ion (TMSe+), dimethylselenoxide (DMSeO), selenomethionine (Semet), Se [IV] and Se [VII]) in the plant extract ranged from 92.9 to 103%. Water extractable Se accounted for 60.4-72.6% of the total Se in the plant. Among the soluble Se compounds in the plant extract, Se-amino acids were 73-85.5%, Se [VI] ranged from 7.5 to 19.5% and non-amino acid organic Se was less than 7%. Se [IV] in most samples was below the detection limit (1 microg/g). This study showed that considerable amounts of the accumulated Se [VI] in the plant was metabolized to Se-amino acids during growth of the plant.     

Analysis of point load test as a method for preliminary geotechnical classification of rocks

This paper deals with the analysis of the point load compression test made on irregular-shaped rock fragments, proposed in the late 50’s by Protodiakonov. An ample revision of the literature on the subject has been made, and a series of tests, using seven different types of rock materials, has been developed. The results obtained from these tests showed that parameters generally used in literature to relate the unconfined compressive (or tensile) strength of materials, resulting from point load tests, can lead to scattered results, due mainly to the scale effect, of great evidence in such tests. It seems possible to obtain compressive (and tensile) strength of rocks, if the ratio between failure load and the distance between load application poins, with a 3/2 exponent, is considered, in field work, as being the "point load strength index".

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Resume L’article présente une analyse critique de l’essai de compression sur échantillons irréguliers de roche, proposé par Protodiakonov vers la fin des années 50. Tout d’abord on a fait une révision de la littérature disponible sur le sujet et, après, une série d’essais sur sept types différents de matériaux. Les résultats obtenus ont montré que les paramètres plus utilisés, dans la littérature, pour définir la résistance à la compression (ou traction) des roches, d’après les essais ponctuels, peuvent provoquer une dispersion très importante des résultats. Cependant, il nous semble valable de suggérer la possibilité de déterminer, sur le chantier, la résistance à la compression (ou traction) des roches, si l’on considère le quotient entre la charge de rupture et la distance entre les deux points d’application de cette charge, le dénominateur à la puissance 3/2, comme "l’indice de charge ponctuelle".