Testing of gas and liquid fuel burners for power and process industries

The object of the present paper is a review of issues related to the testing of gas and liquid fuel burners which are amongst the most important items of equipment in materials processing and energy producing industries. The text gives basic information about fuels, types of burners and their testing and also about modelling of combustion and formation of pollutants, mainly nitrogen oxides. The first two sections of the text provide an overview of fuels and burner types. The most part of the paper deals with an assessment of conditions and equipment required for testing of gas and liquid fuel burners. Conditions that must be satisfied in burner tests in order to preserve comparable operating conditions as in the real application are stressed. Last part provides an outline of the utilisation of statistical analysis methods and modelling by computational fluid dynamics (CFDs) including the formation of pollutants.     

Rayleigh-like instability in the ion-shaping of Au-Ag alloy nanoparticles embedded within a silica matrix

We have studied how spherical 23 ± 3 nm Au(45)Ag(55) nanoparticles embedded within a silica matrix transform into prolate nanorods and nanowires by irradiating them with swift heavy ions. Samples were irradiated at room temperature and normal incidence with 74 MeV Kr and 36 MeV S ions for fluences up to 1.0 × 10(15) cm(-2). We demonstrate the existence of two regimes: (i) below a critical fluence, ～ 2.0 × 10(14) cm(-2), the transformation of the spherical nanoparticle into a nanorod is an individual process, i.e. each nanoparticle transforms into a single nanorod; (ii) for larger fluences the transformation from nanorod to nanowire becomes a collective process, i.e. the break up and dissolution of unstable nanorods contribute to the growth of long nanowires. The passage from the first to the second regime can be interpreted in terms of a Rayleigh-like instability under irradiation. The latter becomes active when the diameter of the nanowire approaches its saturation width under irradiation. Furthermore, we show that the composition of the alloy is only slightly modified during the ion-shaping process. Finally, the energy and the fluence thresholds for deformation and the deformation strain-rate are estimated.     

金属注射成形技术的研究现状

金属注射成形 (MIM)已成为国际粉末冶金领域发展迅速 ,最有前途的一种新型近净成形技术。本文综述了MIM技术的研究现状 ,指出了MIM的发展趋势     

Parasitic systems under the conditions of human pressures (the problems of parasitic contamination)

Antioxidant enzymes are present in sphincter of Oddi nerves and regulate sphincter of Oddi motor function mediated by NO-releasing nerves. Oxygen free radicals (O2-.) produce hydrogen peroxide (H2O2) by the action of superoxide dismutase (SOD). Hydroxyl radical (OH.) has been shown to play an important role as a mediator of H2O2 toxicity. The aims of our study were to determine the effects of H2O2 on sphincter of Oddi motility and if these effects are mediated by OH.. Adult opossums were sacrificed and the sphincter of Oddi removed and placed in a tissue bath containing oxygenated Krebs solution. Force transducers recorded tension in a transverse orientation at two sites along the sphincter of Oddi specimen. H2O2 was added into the tissue bath at concentrations from 0.01 to 0.5%. O2-. radicals were inhibited by the addition of SOD, while OH. was scavenged by the addition of alcohol (ETOH) or dimethyl sulfoxide (DMSO). H2O2 produced a dose-dependent increase in baseline amplitude, frequency, and peak amplitude of contractions. The effect of 0.01% H2O2 on sphincter of Oddi contractile frequency was inhibited by 0.2% ETOH and DMSO, but not by SOD. We conclude that H2O2 has profound effects on sphincter of Oddi motility and that the actions of H2O2 are probably mediated through OH..     

Estradiol-binding properties of a sheep haptoglobin complex with hemoglobin. II. Preliminary data on quantitative characteristics of interaction

The estradiol-binding properties of the sheep haptoglobin-hemoglobin complex (Hp-Hb) have been studied. The time and temperature dependencies of the steroid binding have been established the tightly bound 17 beta-estradiol, which is not detached from the complex during precipitation or extraction, has been shown to form a part of the total amount of the steroid capable of bending to Hp-Hb. Disturbances in the protein-protein interactions between Hp and Hb lead to the dissociation of estradiol as well as to the loss by the protein of its estradiol-binding activity. The values of relative competitive activity for several steroids suggest that some structural elements of the 17 beta-estradiol molecule play a role in estradiol-protein interactions. It is assumed that the Hp-Hb complex has two or more 17 beta-estradiol binding sites.     

Effects of landscape structure on vegetation and some animal groups after agriculture abandonment

This research was carried out on the montane belt of a south-exposed watershed in the Intermediary Alps which have been hit by agriculture abandonment. The aim of the study was to study the relationships between vegetation, landscape mosaic, and two kinds of animals using this space at different scales: roe deer (Capreolus capreolus) and earthworms (lumbricids). Landscape dynamics (post-cultural recolonisation) and landscape structure have been approached by means of the Arc/Info geographical information system (GIS). Several methods used to study on one hand roe deer distribution, and, on the other, earthworm abundance and diversity are developed. Of these, in particular, GIS processing is used to sample earthworms according to vegetation dynamics, and roe deer distribution is related to landscape heterogeneity. Earthworms are more abundant and diversified in the key steps of vegetation dynamics. These lumbricids can be considered as functional indicators of these dynamics. Results also demonstrate that both the vegetation type and the landscape heterogeneity have a direct influence on the use of the space by the roe deer. They show themselves to be structural indicators of the landscape.     

Stereotaxic surgery of temporal lobe epilepsy

Forty patients with temporal epilepsy were operated on with a stereotaxic technique. Eleven patients had a unilateral localization of the epileptic focus, and in 29 bitemporal foci were diagnosed. In evaluating the results of the treatment the dynamics of the epileptic fits, the peculiarities of changes in the mental status, and the degree of social adaptation were taken into consideration. A postoperative improvement was achieved in 73% of the patients with monotemporal lesions, while in those with bitemporal epilepsy and distinct persistent mental disorders the state was improved in 44% of the cases. Indications for the choice of the zone of destruction depending on the clinical peculiarities of the lesion are presented.     

Euclid’s Elements in the Czech Lands

[Terentianus 1st – 2nd century A.D.]

This article is dedicated to Euclid’s Elements, to translations of this work into Czech, and to the translators who have taken on the task of translation. It contains a short overview of the results achieved during a three-year project supported by the Czech Grant Agency.We explored how Euclid’s Elements were spread around the Czech lands.We will try to describe the circumstances that lay behind attempts to translate the Elements into the Czech language.     

A review of drop size measurement in fuel sprays

A detailed review of selected drop size measurement techniques capable of application to practical combustion systems is presented. Attention is restricted to those methods producing quantitative drop size frequency distributions and methods yielding mean spray characteristics are ignored. Comment on the relative merits and restrictions of each method, together with its applicability to particular situations, is made. Some of the techniques described can be applied to measurement of angle of flight and velocity of drops, in addition to their size, in both burning and isothermal sprays. Some indication of future technological advances in the field of drop size measurement is given.