Analysis of Al2O3 Nanostructure Using Scanning Microscopy

It has been reported that the size and shape of the pores depend on the structure of the base metal, the type of electrolyte, and the conditions of the anodizing process. The paper presents thin Al2O3 oxide layer formed under hard anodizing conditions on a plate made of EN AW-5251 aluminum alloy. The oxidation of the ceramic layer was carried out for 40–80 minutes in a three-component SAS electrolyte (aqueous solution of acids: sulphuric 33ml/l, adipic 67 g/l, and oxalic 30 g/l) at a temperature of 293–313K, and the current density was 200–400 A/m2. Presented images were taken by a scanning microscope. A computer analysis of the binary images of layers showed different shapes of pores. The structure of ceramic Al2O3 layers is one of the main factors determining mechanical properties.The resistance to wear of specimen-oxide coating layer depends on porosity, morphology, and roughness of the ceramic layer surface.A3D oxide coatingmodel, based on the computer analysis of images froma scanning electron microscope (Philips XL 30 ESEM/EDAX), was proposed

The finite element method in tribological studies of polymer materials in tribo-pair with oxcide layer

We present an approach to the analysis of mechanisms of the tribological contact of a thin Al2O3 oxide layer formed under hard anodizing conditions on a plate made of the aluminium alloy EN AW-5251. The oxidation of the 50-μm ceramic layer was carried out for 60 min in a three-component electrolyte (SAS), a three-component electrolyte consisting of adipic, sulphuric and oxalic acid, at a temperature of 298.15 K and a current density of 3 A/dm2. A three-dimensional oxide coating model, based on the computer analysis of images from a scanning electron microscope, is proposed. Tribological tests of stresses, strains and dislocations formed in the oxide layer and in the sample material (a block) were conducted. Modified polytetrafluoroethylene (TG15, TGK20/5, TMP12) and polyetheretherketone with carbon fibre and graphite were used as samples for tests in the tribological couple rider-plate of a linear reciprocating friction tester. A tribological couple modelled in the Solid Edge CAD programme was subjected to numerical analyses using the finite element method in the Autodesk Simulation Multiphysics programme under conditions consistent with actual conditions for contact pressures of 0.25, 0.50, and 1.0 MPa

Symulacja i modelowanie nanostruktury warstwy Al2O3 otrzymywanej w elektrolitach trójskładnikowych

Przeprowadzono analizę literatury poświęconej metodom wytwarzania i właściwościom powłok tlenkowych uzyskiwanych na aluminium i jego stopach na potrzeby sformułowania tezy i postawienia celów dysertacji doktorskiej. Zapoznano się z opracowaniami na temat nowoczesnych metod komputerowych i ich wykorzystaniu w modelowaniu i symulacji warstwy tlenkowej, a także analiz numerycznych wspomagających komputerowe badania tribologiczne. Zakres pracy doktorskiej obejmował wytworzenie warstw tlenkowych Al2O3 na stopie aluminium w elektrolitach trójskładnikowych dla zmiennych warunków anodowania twardego. Ukształtowane warstwy tlenkowe poddane zostały komputerowej analizie obrazu na podstawie wykonanych zdjęć SEM. Uzyskane z pomiarów wartości użyto do zbudowania modelu warstwy i zaprogramowania aplikacji symulującej ułożenie włókien. Przeprowadzono komputerowe badania tribologiczne dla węzła tarcia kostka-płytka z zastosowaniem różnych materiałów próbek dla warunków odpowiadających pracy siłowników pneumatycznych. Osiągniętymi celami pracy doktorskiej było poznanie i wyjaśnienie mechanizmów formowania i wzrostu warstwy Al2O3 przy użyciu mikroskopu skaningowego na podstawie zdjęć powłok. Symulacja i modelowanie nanostruktury warstwy tlenkowej Al2O3 wytwarzanej na stopie aluminium w elektrolicie trójskładnikowym. Analiza numeryczna naprężeń, odkształceń i przemieszczeń węzła tarcia tribologicznego w skojarzeniach ślizgowych. Przedstawiona rozprawa doktorska stanowi oryginalne i nowatorskie rozwiązanie problemu wykorzystania metod komputerowych do wspomagania badań tribologicznych węzłów tarcia modyfikowanych materiałów polimerowych w skojarzeniu ze stopem aluminium EN AW-5251 na którym wytworzono warstwy tlenkowe w procesie anodowania. Zamodelowano trójwymiarową warstwę tlenkową wytwarzaną w elektrolitach trójskładnikowych, a także opracowano autorski programu symulujący wygląd morfologii warstwy tlenkowej wytwarzanej w zmiennych warunkach anodowania twardego. Odpowiednie dane wykorzystane na potrzeby modelowania i symulacji uzyskano z KAO zdjęć SEM. Przeprowadzono badania tribologiczne wspomagane modelowaniem CAD i symulacjami komputerowymi wykorzystującymi obliczenia MES, w których zastosowano różne materiały polimerowe dla skojarzenia ślizgowego kostka-płytka celem zastąpienia czasochłonnych i kosztownych badań stanowiskowych

Intracoronary versus intravenous abciximab administration in STEMI patients: overview of current status and open questions

Objectives: To perform a systematic review to provide rationale for intracoronary (IC) abciximab administration in patients with ST-segment elevation myocardial infarction (STEMI), to summarize recent studies comparing IC vs. intravenous (IV) abciximab administration in this setting and to define questions that need to be answered in future trials determining the optimal abciximab regimen. Methods: A search covering the period from January 1993 to June 2011 was conducted by two independent investigators using MEDLINE, CENTRAL and Google Scholar databases. Proceedings from the scientific sessions of ACC, AHA, ESC, TCT and EuroPCR were also considered. Results: IC administration allows one to obtain a much higher concentration of abciximab than IV injection at the culprit lesion. Therefore it is hypothesized that IC abciximab administration provides more efficient GP IIb/IIIa receptor inhibition and more pronounced additional dose-dependent antiplatelet, antithrombotic, and antiinflammatory effects when compared to the IV route. Numerous observational and randomized studies comparing IC vs. IV abciximab in STEMI patients indicated improvement in different surrogate end points (infarct size, obstruction of coronary microcirculation, ST segment resolution, inflammatory mediators and markers of platelet activation) related to IC administration. The evidence supporting clinical benefits associated with IC injection of abciximab comes from one randomized and several non-randomized trials as most of the studies were underpowered to assess clinical outcomes. No difference in bleeding complications was observed between IC and IV regimens. Issues that need to be addressed in future studies include: the use of IC abciximab in combination with thrombectomy, the role of selective delivery systems, and the necessity of a prolonged IV infusion of abciximab after IC bolus administration. Conclusions: An accumulating body of evidence suggests the superiority of IC over IV abciximab administration in STEMI patients. However, further trials are warranted to establish the optimal strategy of abciximab treatment in this setting

Smokers versus non-smokers undergoing percutaneous transluminal coronary angioplasty: The impact of clinical and procedural characteristics on in-hospital mortality

Background: We aimed to compare clinical and procedural characteristics of unselected smokers and non-smokers undergoing percutaneous transluminal coronary angioplasty (PTCA) and to assess their impact on in-hospital mortality. Methods: One thousand consecutive patients treated interventionally were retrospectively enrolled into a single academic centre registry. Results: Smokers (n = 631), in comparison to non-smokers (n = 369), were younger and less likely to be hypertensive, diabetic and female gender. History of myocardial infarction and pre-existing heart failure were also less frequent in the group of smokers. Furthermore, univariate analysis revealed more frequent presentation with acute coronary syndromes (ACS), shorter overall duration of PTCA, shorter exposure to X-rays and lower volume of contrast medium administered in smokers than in non-smokers. Conversely, non-smokers were characterized by considerably higher prevalence of multivessel disease, lower completeness of revascularization and worse final epicardial flow in primary PTCA procedures. Moreover, non-smokers experienced higher crude in-hospital mortality than smokers in the setting of unstable angina/non-ST-segment elevation myocardial infarction (0.0% vs. 6.0%, p = 0.0544) and ST-segment elevation myocardial infarction (6.0% vs. 14.0%, p < 0.02). Smoking status, when adjusted for the baseline characteristics, did not possess any predictive value in terms of in-hospital mortality and surrogates of intervention complexity. Conclusions: A strong trend towards decreased mortality among smokers undergoing PTCA was observed when compared to non-smokers. However, the survival advantage might be fully explained by the younger age of the smokers, their more favourable clinical characteristics and less extensive coronary atherosclerosis. (Cardiol J 2007; 14: 482-492

The ABCs of the Color Code: A Study of Topological Quantum Codes as Toy Models for Fault-Tolerant Quantum Computation and Quantum Phases Of Matter

This thesis is devoted to studying a class of quantum error-correcting codes — topological quantum codes. We explore the question of how one can achieve fault- tolerant quantum computation with topological codes. We treat quantum error-correcting codes not only as a compelling ingredient needed to build a quantum computer, but also as a useful theoretical tool in other areas of physics. In particular, we explore what insights topological codes can provide into challenging questions, such as the classification of quantum phases of matter. In this thesis, we focus on a family of topological codes — color codes, which are particularly intriguing due to the rich physics they display and their computational power. We start by introducing color codes and explaining their basic properties. Then, we show how to perform fault-tolerant universal quantum computation with three-dimensional color codes by transverse gates and code switching. We later compare the resource overhead of the code-switching approach with that of a state distillation scheme. We discuss how to perform error correction with the toric and color codes, as well as introduce local decoders for those two families of codes. By exploiting a connection between error correction and statistical mechanics we estimate the storage threshold error rates for bit-flip and phase-flip noise in the three-dimensional color code. We finish by showing that the color and toric code families in d dimensions are equivalent in a sense of local unitary transformations and explore implications of this equivalence.</p

Radionuclides ^{137}Cs and ^{40}K in the soils of the Tatra National Park (TPN, Poland)

The paper presents the results of radioactivity determination of artificial 137Cs and natural 40K in soil samples taken from the Tatra Mountains in Poland (Tatra National Park – TPN). Soil samples were collected as the cores of 10 cm in diameter and 10 cm in depth. These cores were divided into 3 slices. It has been found that the content of 137Cs was the highest at the sites of the altitude over 1300 m a.s.l. The values of 137Cs concentration in the soils examined varied – from 55.8 Bqźkg–1 (dry mass) (417.8 Bqźm–2) for the Tomanowa Pass (1685 m a.s.l.) to 5111 Bqźkg–1 (dry mass) (8400 Bqźm–2) for the Krzyzne Pass (2112 m a.s.l.). In most cases, the values were lower than the average radiocaesium concentration established for Poland