Search

The aim of the study was to investigate the relationships between the vascular plant species and the associated soil microbial properties at various stages of vegetation development on unclaimed hard coal mine spoil heaps in Upper Silesia (south Poland). The spontaneous vegetation, soil chemistry as well as the activity and structure of microbial communities were recorded on this specific habitat. The colliery heaps were divided into four age classes and the plant species composition and cover abundance were recorded on established plots (2 m × 2 m). The soil microbial activity under the vegetation patches was assessed using fluorescein diacetate hydrolytic activity (FDHA) and the soil microbial biomass and community composition were determined by phospholipid fatty acid (PLFA) biomarkers. Total microbial biomass in soils from the older vegetation plots was significantly higher than those in soils from the younger plots. In all studied samples, microbial communities consisted primarily of bacteria with the dominance of Gram negative bacteria over Gram positive and aerobic microorganisms were more dominant than anaerobic ones. Statistical analysis revealed a correlation between the type of vegetation and microbial community structure.

Abstract:  Experiments were performed on the motion of isolated air bubbles and drops of Fluorinert FC-75 moving in a Dow-Corning silicone oil under the action of an applied temperature gradient in a reduced gravity environment aboard the Space Shuttle in orbit. The disturbance of the imposed temperature field due to the motion of the objects was studied optically using a shearing interferometer with a Wollaston prism and the results of a typical bubble run were compared with theoretical predictions. Also, the liquid velocity field surrounding the bubbles and drops has been qualitatively investigated in a few runs by the observation of tracer particles dispersed in the continuous phase fluid. The measurement techniques are described, and the results for the temperature and flow fields are presented and discussed.

Abstract:  Due to the combined action of buoyancy and thermocapillarity, the flow around a moving or stationary bubble, surrounded by a liquid matrix, exhibits a relative complex structure. The results of recent experiments show two different cases. First the buoyancy force is stronger than the thermocapillary force, secondly, the reverse relationship holds.

Abstract: In this paper, we report experiments conducted on the temperature distribution around a solid sphere that settles slowly in a thermally stratified viscous fluid. The temperature field has been obtained using interferometry. In some cases thermochromic liquid crystal tracers have been used to simultaneously obtain the velocity and the temperature fields. We also describe a theoretical analysis of the problem and compare experimental and theoretical findings and discuss the results. we find that natural convection has a significant influence in determining the nature of the temperature field away from the sphere.

Thermocapillary convection is studied experimentally using particle-image-velocimetry for flow visualization and analysis. This method offers the advantage of measuring the entire flow field (velocity field, streamlines etc.) in a selected plane within the fluid at a given instant of time in contrast to point by point methods like laser-Doppler-velocimetry (LDV). The paper describes the method and presents quantitative results for different Marangoni numbers.

Abstract: This publication deals with the thermocapillary convection of two bubbles in a close proximity under a heated wall. The resultant toroidal vortex rings of the bubbles interfere and cause a distinctive threedimensional flow pattern. Additionally we observed the penetration depth of this flow configuration in dependence on the bubble spacing. Liquid crystal tracer particles serve for simultaneous flow- and temperature monitoring. This novel method is described in some detail. It is a very helpful tool for analyzing heat and mass transfer in liquids.

The in-and out-of-plane angular distributions for fission fragments in coincidence with projectile-like products from the reaction of 252 MeV20Ne with197Au and238U have been measured. The results are compared to a statistical model which has successfully explained?-ray anisotropies from a heavy symmetric system. The agreement is rather good after proper consideration of the direction of the line-of-centers at contact.

Thermocapillary and buoyancy convection is studied experimentally using particle-image-velocimetry with liquid crystal tracers for flow visualization and analysis. This method offers the advantage of measuring the entire flow field (velocity field, temperature distribution etc.) in a selected plane within the fluid simultaneously at a given instant of time in contrast to point by point methods like laser-Doppler-velocimetry (LDV). The paper describes the method and presents quantitative results of both, a thermocapillary and a buoyancy flow experiment. Data of the latter are compared with LDV-results and theoretical predictions, respectively.

In the first of these lectures, the experimental emission probabilities of complex fragments by low energy compound nuclei and their dependence upon energy and Z value are compared to the transtion state rates. In the second part, the high energy multi-fragment emission probabilities are shown to be reducible to the single fragment emission probability through the binomial distribution. The extracted one-fragment emission probabilities have a thermal dependence of the formp=e-B/T. This suggests that multifragmentation is a sequence of thermal binary decays.

Cross sections were measured for fragments (463Cu+12C reactions. Excitation functions were constructed for each Z value, and a nearly complete set of mass-asymmetric barriers has been obtained for75Br. There is excellent agreement between the experimentally determined barriers and the finite-range model calculations, while there is strong disagreement with the liquid-drop model calculations.

Die Anwendung von Flüssigkristallen als Anzeigemedium und Temperaturfeldindikator von Oberflächen sowie Flüssigkeitsströmungen mit Temperaturverteilung hat in den letzten Jahren zunehmend an Bedeutung gewonnen. Insbesondere beim Einsatz zur Temperaturfeldanalyse haben sich Flüssigkristalle zu einem eleganten Meßverfahren entwickelt, welches es erlaubt, ausgedehnte Temperaturfelder sichtbar zu machen und zu analysieren. Hierzu macht man sich die temperaturabhängige Farbreflexion von speziellen Flüssigkristallmaterialien zunutze. Diese in weiten Bereichen der Forschung, Entwicklung und Prozesskontrolle noch wenig bekannte Anwendung ist Gegenstand des vorliegenden Aufsatzes.

In 1991 European Homograft Bank (EHB) initiated a program of cryopreservation and distribution of large arteries to meet a new demand for quality-controlled arterial homo grafts of various sizes. From May 1991 to June 1995, 308 arteries have been registered from 136 donors: 122 brain death cases and 14 cadavers (mean age 34 years, male/female ratio 1.52/1); 263 arteries were cryopreserved (113 aortas, 64 aortic bifur cations, and 86 femoral); 19 were discarded for atherosclerosis (6.7%); 10 batches of arteries were partially or totally discarded because of persistent contamination and further eight batches for positive or doubtful viral serology. One hundred patients were treated in nine European centers with one (N = 69) or more EHB homografts. Indications were: infected prosthesis 70 (17 with aortoenteric fistula); mycotic aneurysm 19 (four ascending aortas, two with bronchial fistula); neoplastic infiltration of subrenal aorta one; extracardiac reconstructions/shunts 10. (continued on next page) (Abstract continued)Results from homograft reconstructions in infected prosthesis or mycotic aneurysm were available in 90 patients. There were 19 early deaths and 24 early complications, three were directly graft-related and included a fatal case of homograft rupture. Sixty- seven vascular cases were followed up from 1 month onward (mean: 16 months): 50 were uneventful; there were nine late deaths, of which two resulted from graft-related digestive hemorrhage; there were eight cases of late complications; three arteries were partly explanted as a result of focal thrombosis. Four patients were lost to follow-up. In the cases of aortoenteric fistula, however, the results were disappointing with only five late survivors of the 16 treated patients. Finally, these results show that cryopreserved arteries seem to perform as well in the midterm as the fresh ones.Both the banking activity of cryopreserved homografts and the short- to mid-term performances of the implants in cases of prosthetic or native arterial infection are very satisfactory, provided no aortoenteric fistula is present. Cryopreserved arteries can also be used for extracardiac shunts and reconstructions.

The connection between the characteristic features of reactions involving very heavy target-projectile combinations (e.g.86Kr+197Au) and lighter systems (e.g.40Ar+natAg) is discussed. Evidence for an empirical scaling law based upon the ratioE/B (center-of-mass kinetic energy to Coulomb barrier) is presented. This scaling is justified in terms of semiquantitative arguments whereby the different charge and angular distribution patterns from light and heavy target-projectile combinations are correlated with different lifetime regimes for the “intermediate complex” as it diffuses along the mass-asymmetry coordinate.

Abstract: The surface tension driven flow in the liquid vicinity of gas bubbles on a heated solid wall has been investigated both, in a reduced gravity environment aboard a sounding rocket, and in an earth-bound experiment. Both experiments deal with temperature gradients within the liquid surrounding of a bubble which cause variations of the surface tension. These, in turn, lead to a liquid flow around the bubble periphery termed thermocapillary or thermal Marangoni-convection. On Earth, this phenomenon is widely masked by buoyancy. We therefore carried out an experiment under reduced gravitational acceleration. In order to simultaneously observe and record the flow field and the temperature field liquid crystal tracers have been applied. These particles offer the feature of selectively reflecting certain wavelengths of incident white light depending on the crystals temperature. Although the bubble injection system did not perform nominally during the flight experiment, some interesting flow characteristics could be observed. Comparison of results obtained in microgravity to data measured on Earth reveal that due to the interaction of thermocapillarity and buoyancy a very compact vortex flow results on ground, while in microgravity the influence on the surface tension driven flow penetrates much deeper into the bulk. This result is of special interest regarding the production of materials in space.

Pendant liquid bridges are defined as pendant drops supporting a solid axisymmetric endplate at their lower end. The stability and shape properties of such bridges are defined in terms of the capillary properties of the system and of the mass and radius of the lower free-floating endplate. The forces acting in the pendant liquid bridge are defined exactly and expressed in dimensionless form. Numerical analysis has been used to derive the properties of a given bridge and it is shown that as the bridge grows by adding more liquid to the system a maximum volume is reached. At this maximum volume, the pendant bridge becomes unstable with the length of the bridge increasing spontaneously and irreversibly at constant volume. Finally the bridge breaks with the formation of a satellite drop or an extended thread. The bifurcation and breakage processes have been recorded using a high-speed video camera with a digital recording rate of up to 6000 frames per second. The details of the shape of the bridge bifurcation and breakage for many pendant bridge systems have been recorded and it is shown that satellite drop formation after rupture is not always viscosity dependent. Bifurcation and breakage in simulated low gravity demonstrated that breakage was very nearly symmetrical about a plane through the middle of the pendant bridge.

Abstract:  Results from experiments on the thermocapillary migration of air bubbles and Fluorinert drops in a Dow–Corning silicone oil aboard a NASA Space Shuttle mission are presented and discussed. The experiments cover a wider range of Marangoni and Reynolds numbers than that attained in a prior flight experiment. The data are consistent with earlier results, and are compared with theoretical predictions. Large air bubbles were found to deform slightly in shape to oblate spheroids while the deformation of even the largest drops was within the uncertainty of the size measurements.

Singles and coincidence charge distributions are combined to illustrate the mechanism for the 220-MeV40Ar+238U reaction. It is found that the apparent peak in the coincidence fragment distribution corresponding toZ=82 (A=208) can be explained in terms of the fissionability of the target-like fragments produced in deep-inelastic collisions rather than as a manifestation of shell effects in compound-nucleus fission, as has been postulated for a similar system.

Application of water electrolyzer generating Brown's gas as an additional source of supplying diesel engine was assessed in this article. Water, due to its slight conductivity must have been enriched with appropriate hydroxides. By-product of combustion of Brown's gas is water vapour. Laboratory site consisted of: hydrogen generator, diesel engine 1,3 Multijet and apparatus for assessment of combustion process. The course of selected parameters of process of functioning of diesel engine of a vehicle with double supply - diesel oil and Brown's gas. Empirical research were conducted in the conditions of static engine work. AVL - Indi Micro 602 was applied to indicate the engine. Selected parameters of combustion process were analysed. If application of the electrolzyer will be justified, the works on analysis of its energy balance and its control will be continued.

BRIght Target Explorer(BRITE) Constellation, the first nanosatellite mission applied to astrophysical research, is a collaboration among Austria, Canada and Poland. The fleet of satellites (6 launched; 5 functioning) performs precise optical photometry of the brightest stars in the night sky. A pioneering mission like BRITE-with optics and instruments restricted to small volume, mass and power in several nanosatellites, whose measurements must be coordinated in orbit-poses many unique challenges. We discuss the technical issues, including problems encountered during on-orbit commissioning (especially higher-than-expected sensitivity of the CCDs to particle radiation). We describe in detail how the BRITEteam has mitigated these problems, and provide a complete overview of mission operations. This paper serves as a template for how to effectively plan, build and operate future low-cost niche-driven space astronomy missions.