The Effect of Implanted Al and/or Y on the Scale Formation on Low-Al Fe20Cr2Al Alloy

The very early stages of the oxidation of an Fe20Cr2Al alloy, unmodified and ion-implanted by aluminium, yttrium and a combination of both elements, Al and Y, were studied at 1100 °C in oxygen using two-stage-oxidation exposures with ¹⁸O₂ as a tracer and subsequent characterisation of the scales using SIMS analyses of distribution of oxygen isotopes and oxide-related negative ion clusters, SEM observations of the surface morphology and photoluminescence spectroscopy analysis of the phase composition. The scales formed in all cases, except for the Al-implanted alloy, exhibited layered structures, with the outer part comprising Fe- and Cr-rich oxide, and the inner part being Al₂O₃, which grew due to a mixed outward–inward mechanism . The alumina sub-layers contained the transient oxides and α-Al₂O₃. Implanted Al significantly affected the mechanism of the scale growth, providing that the scale consisted essentially of α-Al₂O₃, and grew via a mixed inward-outward mechanism typical for scales on alumina formers.     

Assessment of copper surface coverage with corrosion inhibitor using AFM-based local electrical measurements

The paper presents a new method of assessment of metal surface coverage with corrosion inhibitor and thus of inhibitor protective performance. It is based on the atomic force microscopy measurement performed in a contact mode. Apart from topography images the proposed approach allows acquisition of local DC maps and local electrical impedance spectra via application of DC bias voltage or AC perturbation signal between the conductive AFM tip and the substrate. Potentialities of this technique in inhibitor performance monitoring were illustrated on the example of copper/benzotriazole system exposed to elevated humidity environment.     

Testing of thin-walled steel joints fabricated by spot welding and plug welding

Selected methods of joining which can be used for manufacturing and repairing of car bodies by means of welding are presented in this article. Three kinds of 1 mm-thick steel sheets were used in the tests: deep drawing steel (DC04) and two-phase steels of increased high strength (DP600 and DP800). The comparative connections were carried out by means of resistance spot welding and with plug joints made by means of the MAG method and through braze welding. Comparative assessment of the strength and geometrical parameters of the test joints was then conducted.     

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.     

Optimal optical design of thin-film photovoltaic devices

In this paper we report the results of an effort to develop a design tool to optimise any solar cell with thin-film structure. An optical admittance analysis which takes into account the interference effects in the multilayer thin-film system is discussed. This method provides a technique for calculating the optical properties of a thin-film device with a multilayer configuration. It also allows us to explore the nature and magnitude of optical losses in p-i-n type single or multi-junction a-Si : H solar cells, and to optimise the structure of such cells to utilise enhanced interference effects to obtain the maximum possible utilisation of incident solar radiation.     

The influence of porous silicon on junction formation in silicon solar cells

In this work the results of a structural investigation by SEM of porous silicon (PS) before and after diffusion processes are reported. The formation of PS n⁺/p structures were carried out on PS p/p silicon wafers with two methods: from POCl₃ in a conventional furnace and from a phosphorous doped paste in an infrared furnace. Sheet resistance was found to be a strong function of PS structure. Further details on sheet resistance distribution are reported. The electrical contacts in prepared solar cells were obtained by screen printing process, with a Du Ponte photovoltaic silver paste for front contacts and home-prepared silver with 3% aluminium paste for the back ones. Metallization was done in the infrared furnace. Solar cell current–voltage characteristics were measured under an AM 1.5 global spectrum sun simulator. The average results for multi-crystalline silicon solar cells without antireflection coating are: I_sc=720 (mA), V_oc=560 (mV), FF=69%, Eff=10.6% (area 25 cm²).     

Analysis and optimization of a cogeneration system based on biomass combustion

The paper deals with analysis and optimization of the performance of the combustion process in a biomass furnace at a biomass cogeneration plant. For the purpose a thermodynamic model for the biomass burning process in a grate furnace was developed. The mathematical model describes both, the thermal decomposition of the fuel on the grate as well as gas phase combustion in the secondary zone. The presented approach is based on energy equations for each individual step of the biomass combustion process.Measurement results from a biomass-fired cogeneration plant were used to validate the model. Comparison between simulation and measurement results shows good agreement. The model predicts accurately the temperature profiles in the combustion chamber.The presented approach is suitable for model based analysis and optimization of control strategies. The developed model was used to optimize the performance of the recirculation system of the combustion appliance. The simulation based analysis showed, that the flow rate of the recirculated exhaust fumes can be significantly reduced which results in energy savings of 17% of the auxiliary electrical power demand.     

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.