Annular Impinging Jet Controlled by Radial Synthetic Jets

This experimental study focuses on generation and control of annular impinging jets. The annular nozzle used in the investigations was designed with an active flow control system using 12 synthetic jets issuing radially from the central nozzle body. Measurements of the control effects were made on the impingement wall. The data acquisition involved wall pressure and wall mass transfer (by the naphthalene sublimation technique) using air as the working fluid. Also measured was time-mean flow velocity (by a Pitot probe) in the jet flow field. Moreover, flow visualization was carried out. Two main flow-field patterns (A and B) were identified. The patterns differ in the size of the separated-flow recirculation regions that develop attached to the nozzle central body: While pattern A is characterized by a quite small recirculation region (bubble) extending not far from the nozzle exit, pattern B exhibits a large recirculation region, reaching up to the impingement wall, on which it forms a stagnation circle. The control action modifies the flow field, resulting in changes of the corresponding heat/mass transfer distributions. The convective transfer rate on the stagnation circle can be demonstrably enhanced by 20% at a moderate nozzle-to-wall distance, equal to 0.6 of the nozzle outer diameter.     

Early and late results of surgical treatment in patients with primary mediastinal germ cell tumors]

A group of 37 patients--20 (54%) men and 17 (46%) women--aged 2-65, mean 31.6 years, was treated between 1978 and 1995 for different kinds of primary mediastinal germ cell tumours. In 14 (37.8%) of them a mature solid teratoma was diagnosed, in 13 (35.1%)--dermoid cyst, in 5 (13.5%)--malignant teratoma, in 1 (2.7%)--immature teratoma, in 4 (10.8%)--seminoma. Mediastinal tumour was removed completely in 30 (81.1%) patients, partially in 7 (18.9%). Out of 37 patients, 3 (8.1%) died during postoperative time. Out of 26 patients discharged after surgical removal of mature teratomas, all are alive and have been followed-up for 10 years (17 patients) or 5 years (6 patients). Out of 8 discharged after surgical removal of malignant neoplasm, 3 are alive and all of them had primary mediastinal seminoma. One of them has survived 17 years after complete resection, and two patients--7.5 years and 2 years after partial resection and radiotherapy. Mean survival time is 4 years and 2 months for all patients with malignant neoplasm.     

Studies on capillary waves generated by light pulses of Nd3+ - glass laser with ultrasonic Q-switch

In the paper some results of the studies on parameters of capillary waves generated in 18H2N4WA type steel by means of light pulses of Nd³⁺ - glass laser with ultrasonic modulation of Q-factor of the optical resonator have been presented.     

Interactions of Amyloid-β with Membrane Proteins

In developing and developed countries, an increasing elderly population is observed. This affects the growing percentage of people struggling with neurodegenerative diseases, including Alzheimer’s disease. Nevertheless, the pathomechanism of this disease is still unknown. This contributes to problems with early diagnosis of the disease as well as with treatment. One of the most popular hypotheses of Alzheimer’s disease is related to the pathological deposition of amyloid-β (Aβ) in the brain of ill people. In this paper, we discuss issues related to Aβ and its relationship in the development of Alzheimer’s disease. The structure of Aβ and its interaction with the cell membrane are discussed. Not only do the extracellular plaques affect nerve cells, but other forms of this peptide as well.     

A search for optimal acrylic carriers for immobilization of penicillin acylase

Acrylic carriers were obtained by aminolysis of nitrile or ester groups in copolymers or terpolymers synthesized from acrylonitrile, acrylic esters and divinylbenzene or ethylene dimethacrylate in the presence of a mixture of inert diluents. The influence of the supermolecular structure of these carriers, generated during the suspension polymerization by adding a mixture of inert diluents, on the carrier properties was observed. Acrylic carriers for immobilization of penicillin acylase should be obtained from either porous or ‘sol’-type copolymers which aquire after aminolysis the structure of expanded gel.     

The role of microstructure on pesting during oxidation of MoSi2 and Mo(Si,Al)2 at 773 K

The pesting behavior of MoSi₂ and Mo(Si,Al)₂ has been examined in air at 773 K to clarify the origin and mechanism of pesting phenomena and the effect of aluminum on pesting phenomena. The initial cracks play a much more important role than the grain boundaries and the initial oxide layer in pesting. Mo and Si oxidize to amorphous Mo-Si-O simultaneously with about a 200% volume expansion. Therefore, large stress appears at the cracktips and induce many new cracks. MoO₃ vaporizes from the Mo-Si-O layer on the external surface and crack surfaces causing the oxides in the initial cracks to become porous. Oxygen has a short-circuit path to enter the sample in the cracks. Therefore, the partial pressure of oxygen is sufficiently high to allow oxidation of Mo in the materials. The platelet-like MoO₃ grows on the external surface and also in the cracks. Finally, the sample distintegrates into powder. Pesting of Mo(Si,Al)₂ occurs in the same way, however, its rate is much lower than that of MoSi₂. The role of Al is to decrease the initial crack density of the samples from the melt. Other effects of Al might be to decrease the oxygen flux toward the oxide-intermetallic interface and to increase the plasticity of the amorphous oxide being formed in the cracks.     

Causes and Effects of Uncontrolled Water Inrush into a Decommissioned Mine Shaft

Central Europe experienced catastrophic rainfalls and flooding in 2010. This paper discusses a decommissioned shaft that was flooded by surface water, which led to displacement of shaft backfill and an inrush of large amounts of water into an underground pumping station. The weather conditions for the period preceding the inrush, the hydrogeological conditions, the quantity of water that entered the mine dewatering systems, and the underground hydraulic connections are all described. Uncontrolled inflow of water as a cause of backfill saturation and the hazard for active underground infrastructure were analysed. A need to rebuild damaged infrastructure was identified. The case study highlights the need to improve underground mine closure requirements to ensure safe conditions above ground, particularly in densely populated areas.     

Lithography using nano-lens arrays made of light

Abstract

We present a detailed analysis of the appearance intensities for various ion species in strong field multiple ionization based on the Thomas-Fermi model of the atom electronic cloud. Our results differ significantly from the results of a simpler model presented recently. A new range of validity for the adiabatic approximation has been found.     

DEIS evaluation of the relative effective surface area of AISI 304 stainless steel dissolution process in conditions of intergranular corrosion

The results presented in this paper contribute further information concerning examinations of AISI 304 stainless steel dissolution process in conditions of proceeding intergranular corrosion (IG) which have been determined on the basis of dynamic electrochemical impedance spectroscopy (DEIS) measurements. For the first time changes of the relative effective surface area versus time of AISI 304 stainless steel dissolution process in conditions of proceeding intergranular corrosion (IG) in 0.5 M H₂SO₄ + 0.01 M KSCN solution within the range of reactivation polarization scan have been demonstrated. The assessment of the effective surface area of the investigated process was based on approximation to theory of iron dissolution in sulfuric acid medium according to the shape of instantaneous impedance spectra recorded by means of DEIS technique. As a result, it was possible to evaluate that initially changes of the employed equivalent circuit parameters are not only caused by the changes of the relative effective surface area but also by the changes of the AISI 304 SS dissolution process kinetics. Further progress of the examined process implied that changes of the equivalent circuit parameters are only affected by the changes of the relative effective surface area during proceeding IG. Moreover, it was found that the character of changes of the relative effective surface area in conditions of proceeding IG can be described by exponential function.