Effect of diamond-like carbon thin film coated acrylic resin on candida albicans biofilm formation

Purpose: The purpose of this study was to evaluate the effect of diamond-like carbon thin films doped and undoped with silver nanoparticles coating poly(methyl methacrylate) (PMMA) on Candida albicans biofilm formation. The control of biofilm formation is important to prevent oral diseases in denture users. Materials and Methods: Forty-five PMMA disks were obtained, finished, cleaned in an ultrasonic bath, and divided into three groups: Gc, no surface coating (control group); Gdlc, coated with diamond-like carbon film; and Gag, coated with diamond-like carbon film doped with silver nanoparticles. The films were deposited using a reactive magnetron sputtering system (physical vapor deposition process). The specimens were characterized by optical profilometry, atomic force microscopy, and Rutherford backscattering spectroscopy analyses that determined differences in chemical composition and morphological structure. Following sterilization of the specimens by γ-ray irradiation, C. albicans (ATCC 18804) biofilms were formed by immersion in 2 ml of Sabouraud dextrose broth inoculated with a standardized fungal suspension. After 24 hours, the number of colony forming units (cfu) per specimen was counted. Data concerning biofilm formation were analyzed using ANOVA and the Tukey test (p < 0.05). Results: C. albicans biofilm formation was significantly influenced by the films (p < 0.00001), reducing the number of cfu, while not affecting the roughness parameters (p > 0.05). The Tukey test showed no significant difference between Gdlc and Gag. Films deposited were extremely thin (∼50 nm). The silver particles presented a diameter between 60 and 120 nm and regular distribution throughout the film surface (to Gag). Conclusion: Diamond-like carbon films, doped or undoped with silver nanoparticles, coating the base of PMMA-based dentures could be an alternative procedure for preventing candidosis in denture users. © 2013 by the American College of Prosthodontists.

Si-based thin film coating on Y-TZP: Influence of deposition parameters on adhesion of resin cement

This study evaluated the influence of deposition parameters for Si-based thin films using magnetron sputtering for coating zirconia and subsequent adhesion of resin cement. Zirconia ceramic blocks were randomly divided into 8 groups and specimens were either ground finished and polished or conditioned using air-abrasion with alumina particles coated with silica. In the remaining groups, the polished specimens were coated with Si-based film coating with argon/oxygen magnetron discharge at 8:1 or 20:1 flux. In one group, Si-based film coating was performed on air-abraded surfaces. After application of bonding agent, resin cement was bonded. Profilometry, goniometry, Energy Dispersive X-ray Spectroscopy and Rutherford Backscattering Spectroscopy analysis were performed on the conditioned zirconia surfaces. Adhesion of resin cement to zirconia was tested using shear bond test and debonded surfaces were examined using Scanning Electron Microscopy. Si-based film coating applied on air-abraded rough zirconia surfaces increased the adhesion of the resin cement (22.78 ± 5.2 MPa) compared to those of other methods (0-14.62 MPa) (p = 0.05). Mixed type of failures were more frequent in Si film coated groups on either polished or air-abraded groups. Si-based thin films increased wettability compared to the control group but did not change the roughness, considering the parameters evaluated. Deposition parameters of Si-based thin film and after application of air-abrasion influenced the initial adhesion of resin cement to zirconia. © 2013 Elsevier B.V. All rights reserved.

Ion beam analysis of a-C:H films on alloy steel substrate

An a-C:H thin film deposited by plasma immersion ion implantation and deposition on alloy steel (16MnCr5) was analyzed using a self-consistent ion beam analysis technique.In the self-consistent analysis, the results of each individual technique are combined in a unique model, increasing confidence and reducing simulation errors.Self-consistent analysis, then, is able to improve the regular ion beam analysis since several analyses commonly used to process ion beam data still rely on handling each spectrum independently.The sample was analyzed by particle-induced x-ray emission (for trace elements), elastic backscattering spectrometry (for carbon), forward recoil spectrometry (for hydrogen) and Rutherford backscattering spectrometry (for film morphology).The self-consistent analysis provided reliable chemical information about the film, despite its heavy substrate.As a result, we could determine precisely the H/C ratio, contaminant concentration and some morphological characteristics of the film, such as roughness and discontinuities.© 2013 Elsevier B.V.All rights reserved.

Influência da temperatura e do tipo de substrato em filmes de GaN depositados por magnetron sputtering reativo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The mineralizing fluid in the Piaba gold deposit, São Luís cratonic fragment (NW-Maranhão, Brazil) based on fluid inclusion studies in quartz veins

O depósito aurífero de Piaba tornou-se a primeira mina em operação no fragmento cratônico São Luís, noroeste do Maranhão. Seu ambiente geológico compreende rochas metavulcanossedimentares do Grupo Aurizona e granitoides da Suíte Tromaí, entre outras unidades menores, formadas em ambiente de arcos de ilhas entre 2240 e 2150 Ma, juntamente com outras unidades menores. A mineralização é caracterizada por uma trama stockwork de veios e vênulas de quartzo com seus halos de alteração (clorita + muscovita + carbonato + pirita + calcopirita e ouro) hospedada em um granodiorito granofírico fino (Granófiro Piaba) e em rocha subvulcânica andesítica do Grupo Aurizona. O corpo mineralizado é espacialmente limitado à zona de cisalhamento ENE-WSW rúptil-dúctil (Falha Piaba). Estudos petrográficos, microtermométricos e por espectroscopia microRaman no quartzo definiram inclusões aquo-carbônicas bifásicas e trifásicas, produzidas por aprisionamento heterogêneo durante separação de fases, e fluidos aquosos tardios. A solução mineralizadora corresponde a um fluido aquo-carbônico composto por CO₂ (5 - 24 mol%, densidade de 0,96 - 0,99 g/cm³), H₂O (74 - 93 mol%), N₂ (< 1 mol%), CH₄ (<1mol%) e 5,5 % em peso NaCl equivalente. O minério depositou a 267 - 302ºC e 1,25 - 2,08 kbar, correspondendo a profundidades de 4 a 7 km, em consonância com o regime estrutural. A composição e o intervalo de P-T do fluido mineralizador, combinados com o caráter redutor (log ƒ_O2 -31,3 a -34,3) e a sulfetação da rocha hospedeira, sugerem que o ouro foi transportado como um complexo sulfetado. O minério foi depositado em consequência da separação de fase, redução da atividade de enxofre e da ƒO₂ pela interação fluido-rocha.

Left ventricular sphericity index predicts systolic dysfunction in rats with experimental aortic regurgitation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Innovative low temperature plasma approach for deposition of alumina films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biomonitoring study of seasonal anthropogenic influence at the Itamambuca beach (SP, Brazil)

The present work is focused on the study of a seasonal anthropogenic influence on the beach of Itamambuca (Ubatuba, SP, Brazil) carried out using Atherinella brasiliensis as biomonitor. In total 84 fish were caught between July 2004 and February 2005 in different locations at the beach and inside the Itamambuca river. The fish were pooled according to catch and their musculature was analyzed by Particle-Induced X-ray Emission (PIXE) and Rutherford Backscattering (RBS) techniques. While the concentration of light (matrix) elements like C and O were obtained using the RBS technique, major (Na, Mg, P, S, Cl, K and Ca) and trace (Si, Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br and Sr) elements were measured by PIXE. The results show that differences were observed for several elemental concentrations of fish tissue between high season (spring-summer) and low season (winter-fall), indicating that increased human activity in the beach during high season may have some impact on the beach ecosystem. The role of the water salinity in the results is also discussed. (C) 2009 Elsevier B.V. All rights reserved.

Experimental study of the He stopping power into Al2O3 films

In the present work, we report experimental results of He stopping power into Al2O3 films by using both transmission and Rutherford backscattering techniques. We have performed measurements along a wide energy range, from 60 to 3000 key, covering the maximum stopping range. The results of this work are compared with previously published dap-, showing a good agreement for the high-energy range, but evidencing discrepancies in the low-energy region. The existing theories follow the same tendency: good theoretical-experimental agreement for higher energies, but they failed to reproduce previous and present results in the low energy regime. On the other hand it is interesting to note that the semi-empirical SRIM code reproduces quite well the present data. (C) 2012 Elsevier B.V. All rights reserved.

Dynamik unterkühlter Flüssigkeiten in Filmen und Röhren

GERMAN:Im Rahmen der vorliegenden Arbeit soll der Einfluß einerräumlichen Beschränkung auf die Dynamik einer unterkühltenFlüssigkeit charakterisiert werden. Insbesondere sollgeklärt werden, welche Rolle die Kooperativität derTeilchenbewegung bei niedrigen Temperaturen spielt. Hierzuuntersuchen wir mit Hilfe einer Molekulardynamik-Computersimulation die dynamischen Eigenschaften eineseinfachen Modellglasbildners, einer binäre Lennard-Jones-Flüssigkeit, für Systeme mit unterschiedlichen Geometrienund Wandarten. Durch geschickte Wahl der Wandpotentiale konnte erreichtwerden, daß die Struktur der Flüssigkeit mit der im Bulknahezu identisch ist.In Filmen mit glatten Wänden beobachtet man, daß dieDynamik der Flüssigkeit in der Nähe der Wand starkbeschleunigt ist und sich diese veränderte Dynamik bis weitin den Film ausbreitet. Den umgekehrten Effekt erhält man,wenn man eine strukturierte, rauhe Wand verwendet, in derenNähe die Dynamik stark verlangsamt ist.Die kontinuierliche Verlangsamung bzw. Beschleunigung derDynamik vom Verhalten an der Oberfläche zum Bulkverhaltenin genügend großem Abstand zur Wand können wirphänomenologisch beschreiben. Hieraus kann mancharakteristische dynamische Längenskalen ablesen, die mitsinkender Temperatur kontinuierlich anwachsen, d.h. derBereich, in dem die Existenz der Wand einen (indirekten)Einfluß auf die Dynamik eines Flüssigkeitsteilchens hat,breitet sich immer weiter aus. Man kann daher vonBereichen kooperativer Bewegung sprechen, die mit sinkenderTemperatur anwachsen.Unsere Untersuchungen von Röhren zeigen, daß aufgrund desstärkeren Einflusses der Wände die beobachteten Effektegrößer sind als in Filmgeometrie. Bei Reduzierung derSystemgröße zeigen sich immer größere Unterschiede zumBulkverhalten.

Complex tracer mobilities in polymer networks revealed by fluorescence correlation spectroscopy

Gels are elastic porous polymer networks that are accompanied by pronounced mechanical properties. Due to their biocompatibility, ‘responsive hydrogels’ (HG) have many biomedical applications ranging from biosensors and drug delivery to tissue engineering. They respond to external stimuli such as temperature and salt by changing their dimensions. Of paramount importance is the ability to engineer penetrability and diffusion of interacting molecules in the crowded HG environment, as this would enable one to optimize a specific functionality. Even though the conditions under which biomedical devices operate are rather complex, a bottom-up approach could reduce the complexity of mutually coupled parameters influencing tracer mobility. The present thesis focuses on the interaction-induced tracer diffusion in polymer solutions and their homologous gels, probed by means of Fluorescence Correlation Spectroscopy (FCS). This is a single-molecule-sensitive technique having the advantage of optimal performance under ultralow tracer concentrations, typically employed in biosensors. Two different types of hydrogels have been investigated, a conventional one with broad polydispersity in the distance between crosslink points and a so-called ‘ideal’, with uniform mesh size distribution. The former is based on a thermoresponsive polymer, exhibiting phase separation in water at temperatures close to the human body temperature. The latter represents an optimal platform to study tracer diffusion. Mobilities of different tracers have been investigated in each network, varying in size, geometry and in terms of tracer-polymer attractive strength, as perturbed by different stimuli. The thesis constitutes a systematic effort towards elucidating the role of the strength and nature of different tracer-polymer interactions, on tracer mobilities; it outlines that interactions can still be very important even in the simplified case of dilute polymer solutions; it also demonstrates that the presence of permanent crosslinks exerts distinct tracer slowdown, depending on the tracer type and the nature of the tracer-polymer interactions, expressed differently by each tracer with regard to the selected stimulus. In aqueous polymer solutions, the tracer slowdown is found to be system-dependent and no universal trend seems to hold, in contrast to predictions from scaling theory for non-interacting nanoparticle mobility and empirical relations concerning the mesh size in polymer solutions. Complex tracer dynamics in polymer networks may be distinctly expressed by FCS, depending on the specific synergy among-at least some of - the following parameters: nature of interactions, external stimuli employed, tracer size and type, crosslink density and swelling ratio.

Foundations of stochastic geometry and theory of random sets

The first section of this chapter starts with the Buffon problem, which is one of the oldest in stochastic geometry, and then continues with the definition of measures on the space of lines. The second section defines random closed sets and related measurability issues, explains how to characterize distributions of random closed sets by means of capacity functionals and introduces the concept of a selection. Based on this concept, the third section starts with the definition of the expectation and proves its convexifying effect that is related to the Lyapunov theorem for ranges of vector-valued measures. Finally, the strong law of large numbers for Minkowski sums of random sets is proved and the corresponding limit theorem is formulated. The chapter is concluded by a discussion of the union-scheme for random closed sets and a characterization of the corresponding stable laws.

Controls on the Basal Water Pressure in Subglacial Channels Near the Margin of the Greenland Ice Sheet

Assuming a channelized drainage system in steady state, we investigate the influence of enhanced surface melting on the water pressure in subglacial channels, compared to that of changes in conduit geometry, ice rheology and catchment variations. The analysis is carried out for a specific part of the western Greenland ice-sheet margin between 66 degrees N and 66 degrees 30' N using new high-resolution digital elevation models of the subglacial topography and the ice-sheet surface, based on an airborne ice-penetrating radar survey in 2003 and satellite repeat-track interferometric synthetic aperture radar analysis of European Remote-sensing Satellite 1 and 2 (ERS-1/-2) imagery, respectively. The water pressure is calculated up-glacier along a likely subglacial channel at distances of 1, 5 and 9 km from the outlet at the ice margin, using a modified version of Rothlisberger's equation. Our results show that for the margin of the western Greenland ice sheet, the water pressure in subglacial channels is not sensitive to realistic variations in catchment size and mean surface water input compared to small changes in conduit geometry and ice rheology.

How does the ascending aorta geometry change when it dissects?

OBJECTIVES The purpose of this study is to delineate changes in aortic geometry and diameter due to dissection. BACKGROUND Aortic diameter is the major criterion for elective ascending aortic replacement for dilated ascending aortas to prevent aortic dissection. However, recommendations are made on the basis of clinical experience and observation of diameters of previously dissected aortas. METHODS Six tertiary centers on 2 continents reviewed their acute aortic dissection type A databases, which contained 1,821 patients. Included were all non-Marfan patients with nonbicuspid aortic valves who had undergone computed tomography angiography <2 years before and within 12 h after aortic dissection onset. Aortic geometry before and after dissection onset were compared. RESULTS Altogether, 63 patients were included (27 spontaneous and 36 retrograde dissections, median age 68 [57; 77] years; 54% were men). In all but 1 patient, maximum ascending aortic diameter was <55 mm before aortic dissection onset. The largest increase in diameter and volume induced by the dissection were observed in the ascending aorta (40.1 [36.6; 45.3] mm vs. 52.9 [46.1; 58.6] mm, +12.8 mm; p < 0.001; 124.0 [90.8; 162.5] cm(3) vs. 171.0 [147.0; 197.0] cm(3), +47 cm(3); p < 0.001). Mean aortic arch diameter increased from 39.8 (30.5; 42.6) mm to 46.4 (42.0; 51.6) mm (+6.6 mm; p < 0.001) and descending thoracic aorta diameter from 31.2 (27.0; 33.3) mm to 34.9 (30.9; 39.5) mm (+3.7 mm; p < 0.001). Changes in thoracic aorta geometry were similar for spontaneous and retrograde etiology. CONCLUSIONS Geometry of the thoracic aorta is affected by aortic dissection, leading to an increase in diameter that is most pronounced in the ascending aorta. Both spontaneous and retrograde dissection result in similar aortic geometry changes.